LogoClive's UndergrounD Line Guides

"Aldgate is a junction, and there was a network of points. On these his eager, questioning eyes were fixed, and I saw on his keen, alert face that tightening of the lips, that quiver of the nostrils, and concentration of the heavy tufted brows which I knew so well.

'Points,' he muttered, 'the points.'"

- The Bruce-Partington Plans
Sir Arthur Conan Doyle

LogoCircle Line

A Subsurface Line

[last modified 2007-12-11]

Rolling stock


The early success of the Metropolitan Railway (now the Hammersmith & City Line) prompted a huge number of proposals for other railways. Parliamentary committees in 1863-4 evaluated them and decided that the best thing would be an "inner circuit" (as it was first known) connecting both ends of the Metropolitan route (then Paddington and Farringdon) with the main-line railway stations on the north side of the Thames but serving the south (Victoria, Charing Cross, Blackfriars, and Cannon Street). The route first proposed ran south from Moorgate to Cannon Street, but this was soon amended to the present alignment to allow connection with three additional termini: Liverpool Street, Broad Street, and Fenchurch Street. However, this change also forced an awkward doubling-back at Aldgate, reducing the desirability of the line for local traffic and greatly increasing the cost of construction due to high prices in the City of London.

The Metropolitan obtained powers to extend itself to Tower Hill (1) in the east and South Kensington in the west, in both cases along the present route of the Circle Line. The latter extension also reinstated the Praed Street station that had originally been planned for Paddington but later dropped. Because so much capital would have to be raised to build the rest of the Circle, it was found expedient to start a separate company for this purpose. It was planned that the two companies would be merged as soon as practical, and so the similar name "Metropolitan District Railway" was chosen.

However, the MDR was a much less profitable company than the Metropolitan (whose financial performance was never even approached by any other line), and the Metropolitan's shareholders blocked the merger. This decision was clearly not in the public interest, but even considering only their own financial interests, it is hard to say whether or not it was a smart one. By rejecting the MDR's financial obligations, the Metropolitan acquired an enemy. For years thereafter, the situation was almost one of warfare - often to the detriment of passengers - and the relationship only really became friendly after the completion of electrification in 1905 and the consequent improvement in the MDR's finances.

Photo [157kb] and info

After the break, the MDR was commonly referred to as the District Railway (and so became the District Line). There were many examples of the unbridled competition, of which three will suffice. Shortly after the Circle was completed, there was a dispute over access to a siding at South Kensington, culminating in one company chaining a steam engine to the tracks while the other tried to tow it away. For some years each company maintained its own booking office at each Circle station, and the unsuspecting passenger would be sold a ticket, not for the quicker option, but for whichever direction of travel around the Circle gave the vendor a greater share of the income. And the most extreme case of all was when the MDR constructed, without Parliamentary authorisation, a duplicate pair of tracks from High Street Kensington to Gloucester Road - the "Cromwell Curve" - just so it could demand an increase in its share of the mileage-based Circle revenues because it had a greater mileage (it took a 19-year lawsuit to establish that this idea was flawed).

Returning to the 1860s: the Metropolitan rapidly constructed the western extension, and the District (as it soon became known) continued from there to Mansion House. However, the District could not afford to complete the rest of the line to Tower Hill, while the Metropolitan suddenly viewed the eastern section as a threat - the District would take much of its traffic into the City - and tried to abandon its own planned route to Tower Hill. However, business interests in the City were not willing to accept this, and formed the Metropolitan Inner Circle Completion Railway Company in 1874. This spurred the Metropolitan into extending rapidly as far as Aldgate, and forced the two railways into negotiation.

As a result, the Metropolitan bought out the new company and, in conjunction with the District, implemented its plans to complete the Circle and simultaneously connect both lines to the East London Line. The arrangement received Parliament's approval in 1879 and the work was started relatively rapidly. As well as the increased costs of the final route, further trouble and cost came from a requirement (probably imposed as a reaction to the disruption caused by previous construction) to excavate only at night and replace the road every morning. The Circle was completed in 1884, and from then on both companies would run trains all the way round. Even then the District were not completely committed to the Circle, and for some time they had plans to make Tower Hill (2) a four-track station where many trains from both directions would terminate.

Readers will note the name "Inner Circle", still used by many Londoners. "Inner" simply referred to the central position of the route with respect to London and its railways; the name was in use by 1869, well before the actual completion of the circuit. In fact, over the following decade, three other services, each in the form of a horseshoe and, in two cases, sharing track with the Inner Circle, were given names obviously modelled after it:

Middle Circle
Hammersmith & City Line from Moorgate via Latimer Road to Kensington (Olympia), then District Line to Mansion House. This service ran from 1872 to 1906, though the latter terminus was cut back twice, to Earl's Court in 1900 and Kensington (Olympia) in 1905. The service was operated by the Hammersmith & City and District Railways. [For services on this section after 1906, see the Hammersmith & City Line page.]
Outer Circle
NLR from Broad Street to Willesden Junction, then WLR to Kensington (Olympia), then various routes: In 1912 it was reduced to a Willesden-Earl's Court shuttle, and after bomb damage to the track at Kensington (Olympia) it was finally abandoned in 1940. This was essentially a LNWR service, though the District provided the locomotives on its section and operated the shuttle from 1914-07-01 to 1914-11-21 inclusive (while the LNWR obtained electric trains).
Super Outer Circle
Midland Railway from St. Pancras to Cricklewood, then Midland & South Western Joint to Acton Central, then NLR to Acton Lane Junction (see the District Line) via a chord (since removed), then District Line to Earl's Court. This was operated by the Midland Railway for a short period starting in 1878.

Note that the Inner and Middle Circles were essentially "Underground" services on Underground routes, while the Outer and Super Outer Circles were essentially main-line routes using sections of Underground lines but operated by main-line companies.

The rivalry between the two companies was to strike one more time, at electrification in 1905. The District, by then in the hands of Yerkes, chose the four-rail DC system that is still in use today. The Metropolitan, on the other hand, wanted to use the Ganz three-phase AC system, involving two overhead wires. The dispute went to arbitration, and the District won. On 1905-07-01, which should have been the first day of electric operation of the Circle, it turned out that the Metropolitan had used narrower collector shoes and more accurately placed conductor rails, and their trains had to be confined to the northern side until modified.

Since then the Circle Line has mostly operated unchanged (though see Services for notes on some experiments). It gained its own identity in about 1949; until then the Inner Circle was just one of the services run by the Metropolitan and District Lines.

In 1999 it was necessary to close the line from High Street Kensington to Gloucester Road in order to repair the covered way. The original plan was to have trains run from both Wimbledon and Kensington (Olympia) almost completely round the Circle and then back to their origin. This approach collapsed on the first day of this service and was never made to operate properly; within a week the Circle Line was closed completely for the duration of the work.


For dates before the completion of the Circle, [D] and [M] indicate the company - District and Metropolitan respectively - initially operating that section. Further details can be found under the appropriate Lines. From the opening of the final section, both companies (and both the subsequent LU operating units) ran trains around the whole Circle. After a chaotic opening, with the companies alternating trains in both directions, the Metropolitan ran all Outer Rail (clockwise) trains and 2 out of 7 Inner Rail (anticlockwise) ones, while the District ran the remaining 5. This asymmetry was later removed, and the District finally withdrew in 1990.

[MC] indicates the "Middle Circle" service, [OC] the "Outer Circle" service, and [SC] the "Super Outer Circle".

key to symbols

1863-01-10 [5] Farringdon to [Praed Street Junction] opened [M]
X King's Cross St. Pancras
1865-12-23 1 Moorgate to Farringdon opened [M]
< Farringdon
1867-09-01 Broad Street to Kensington (Olympia) started [OC]
1868-10-01 4 [Praed Street Junction] to Gloucester Road opened [M]
1868-12-24 0 Gloucester Road to South Kensington opened [M]
3 South Kensington to Westminster opened [D]
1869-01-01 Kensington (Olympia) to Victoria started [OC]
1870-05-30 2 Westminster to Blackfriars opened [D]
1871-07-03 0 Blackfriars to Mansion House opened [D]
0 Cromwell Curve opened[1] [D]
1872-01-31 Kensington (Olympia) to Victoria withdrawn [OC]
1872-02-01 Kensington (Olympia) to Mansion House started [OC]
1872-08-01 Moorgate to Mansion House via Kensington (Olympia) started [MC]
1874-02-02 % Liverpool Street (main line station) [GER]
1875-02-01 0 Liverpool Street (main line station) to Moorgate opened [M][MC]
1875-07-11 Liverpool Street (main line station) to Moorgate closed [M][MC]
1875-07-12 0 Liverpool Street to Moorgate opened [M][MC]
1876-11-18 0 Aldgate to Liverpool Street opened [M]
1876-12-04 Aldgate to Liverpool Street started [MC]
1878-05-01 St. Pancras to Earl's Court started [SC]
1880-09-30 St. Pancras to Earl's Court withdrawn [SC]
1882-09-25 0 Tower Hill (1) to Aldgate opened [M]
1884-10-06 3 Mansion House to Tower Hill (1) opened [D]
1884-10-12 - Tower Hill (1)
1900-06-30 Earl's Court to Mansion House withdrawn [MC]
1905-01-31 Kensington (Olympia) to Earl's Court withdrawn [MC]
1905-07-01 * each company separately
1905-09-13 * circular service one-day trial
1905-09-24 * circular service
1905-12-04 * Earl's Court to Mansion House [OC]
1906-11-04 Aldgate to Latimer Road withdrawn [MC]
1907-11-03 District service withdrawn
1908-10-01 District service restored
1908-12-31 Earl's Court to Mansion House withdrawn [OC]
1912- Broad Street to Willesden Junction withdrawn [OC]
1914-05-01 * Willesden Junction to Earl's Court [OC]
1926-10-31 District service cut back to Sundays only
1940-10-02 Willesden Junction to Earl's Court withdrawn [OC]
1940-10-15 Farringdon to Baker Street closed intermittently[2]
1941-03-09 -= King's Cross Thameslink
1941-03-14 + King's Cross St. Pancras
1941-05-10 Farringdon to Baker Street closed
1941-07-21 1 Euston Square to Baker Street reopened
1941-10-04 [1] Farringdon to Euston Square reopened
+ King's Cross St. Pancras
1956-02-12 Cromwell Curve closed
1967-02-04 - Tower Hill (2)
1967-02-05 + Tower Hill (1)
1989-10-29 - Mansion House (renovation and entrance works)
1990-05-13 District service withdrawn
1991-02-11 + Mansion House
1996-01-22 - Bayswater (refurbishment and congestion relief)
1996-03-18 + Bayswater
1999-06-11 Circle service withdrawn[3]
High Street Kensington to Gloucester Road closed
Tower Hill (1) to Aldgate closed
1999-08-23 Circle service restored
0 High Street Kensington to Gloucester Road reopened
0 Tower Hill (1) to Aldgate reopened
2001-05-11 - Great Portland Street, Outer Rail only
2001-05-28 + Great Portland Street, Outer Rail only
2005-01-29 - Bayswater, Outer Rail only (refurbishment)
2005-02-12 - Bayswater, Inner Rail only (refurbishment)
2005-02-13 + Bayswater, Outer Rail only
2005-02-28 + Bayswater, Inner Rail only
2005-07-07 Circle service withdrawn (bomb explosions on trains at Aldgate and Edgware Road)
2005-08-04 Circle service restored[4]
2007-12-08 - King's Cross Thameslink

[1] The Cromwell Curve saw regular service for about two months, after which it was only used when necessary for operational reasons.

[2] Following bomb damage near King's Cross on 1940-10-16 services ran intermittently in this section for the next few months.

[3] This closure was for repairs to the covered way carrying the tracks from High Street Kensington to Gloucester Road. Trains ran for a few days after the official closure date; see History for more details.

[4] A limited service ran during the peak hours of the 4th and 5th, and there was no service at all on the 6th and 7th (a weekend). Normal service resumed on the 8th.


The line is basically underground throughout, though various stretches and stations are in cuttings. The two tracks of the route are known within LU as the "Inner Rail" (Aldgate to Paddington to Embankment to Aldgate, with increasing km) and the "Outer Rail" (the other direction). Though these terms are unknown to the general public nowadays, at one time tickets were explicitly labelled "I" or "O" (or in a few cases "E", indicating either way).

At Aldgate the outer two platforms are used by the Circle, while the centre two (which can only be entered from the west end) are used by the Metropolitan. The former are the only platforms used that are exclusive to the Circle, and are used to regulate trains to time. The only other exclusive part of the route is from High Street Kensington to Gloucester Road. The Inner Rail merges with the eastbound District Line west of the latter, but the Outer Rail is separate until just west of South Kensington; this allows a Circle Line train to be held for an eastbound District Line train at the flat junction without any delay to following westbound District trains (this had been a major cause of disruption until the reconstruction of the area in 1957).

From Blackfriars to Westminster, the line runs within the Embankment along the north side of the Thames; next to it is a major sewer, part of the system which brought decent sanitation to London for the first time in the 19th century. Construction of the embankment, road, sewer, and District Line was planned as a single integrated project, but the MDR did not have enough capital; instead, the other components were completed, then torn up and rebuilt when the District's cut-and-cover construction came. The lowest point on the Circle is Westminster station, 4.0m (13') below Thames high tide level, and the highest is Edgware Road, at 31.4m (103') above high tide.


Operationally the Circle Line is not separate, but is merely a second service of the Hammersmith & City Line, and trains are shared between the two. The Circle trains run continually throughout the day, nominally at 8 minute intervals, with various arrangements being used at the start and end of service, as some trains are stabled at places like Hammersmith Depot (and formerly Neasden). In addition, on weekdays after the evening peak, some trains transfer from the Circle to the Hammersmith/Whitechapel route, a few by running directly between Aldgate East and Tower Hill.

Until nationalization, the Metropolitan and District services remained mostly independent. But with the amalgamation, some experiments were made to see if there was a better way integrate the various subsurface lines. Many variations were proposed - the most complex being Uxbridge to Wimbledon via Finchley Road and Aldgate - and even tried - such as Uxbridge to Barking via Finchley Road - but it eventually became clear that they simply led to confusion, and in addition a delay anywhere on the system would propagate bit by bit until the entire system was affected. Instead, it was clear that the best way was to have several independent services with a minimal duplication of traffic. The only new service to survive was the Hammersmith & City peak extension to Barking.

In the 1950s and 1960s there was a curious arrangement whereby Putney Bridge to Edgware Road trains were extended over the north side of the Circle to Aldgate on the last weekday before a bank holiday weekend (that is, several Fridays and Maundy Thursday). From 1968 until 1972, the District Line services to Edgware Road were similarly extended to Aldgate on Saturday afternoons.

More recently, other experiments have been tried. For example, to reduce the number of trains used on Sundays, the Hammersmith & City and Circle services were merged, with trains running from Hammersmith, once round the Circle, and then to Whitechapel (or the reverse, of course). Another example was the extension of the Kensington (Olympia) shuttle to Edgware Road outside peak hours. But none of these have survived long, though the latter still operates in the early morning.

The minimum running time for a complete circuit is 50 minutes, but nearly all trains have a scheduled wait at Aldgate to help them fit into the other services on these lines.


Diagram CBD


key to notation

Upwards on the page is the "Outer Rail" (clockwise) and downwards is the "Inner Rail" (anticlockwise).

Distances on the District Line section are calculated via the Inner Rail. As shown below, the distance via the Outer Rail is about 40m longer (the Circle/District boundary is also at a different point on the two tracks).

40=06 [-] [Minories Junction]
336812 40.19 [O=tt=I] [Z1] Aldgate
335813 40.32 [-] [Aldgate Junction]
331815 40.81 [OP] [Z1] Liverpool Street
324814 41.33 [=OI=tt=tt=] [Z1] Moorgate
320818 41.96 [=OI=sn=] [Z1] Barbican
315818 42.47 [=OI=sn=] [Z1] Farringdon
304829 43.90 [='A'sn'B'==#OI#=] [Z1] (King's Cross Thameslink)
302828 44.32 [CPX] [Z1] King's Cross St. Pancras
294823 45.17 [OPX] [Z1] Euston Square
288821 45.79 [OPX] [Z1] Great Portland Street
280820 46!59 [-] [Baker Street Junction]
279819 46.72 [t4=sn=1t =5OI6=] [Z1] Baker Street
272817 47.44 [O=ew=I] [Z1] Edgware Road (1)
269814 47.76 [-] [Praed Street Junction]
266811 48.26 [OPX] [Z1] Paddington
258808 49.24 [OPX] [Z1] Bayswater
252804 50.03 [OPX] [Z1/2] Notting Hill Gate
255795 50.97 [t= t=OI= X] [Z1] High Street Kensington
51.62 [-] [Circle/District boundary (Inner Rail)]
260789 51=7 [-] [Gloucester Road junction]
262788 51=86 [=wO=I=] [Z1] Gloucester Road
269788 52=58 [O=I =] [Z1] South Kensington
280786 53=82 [OP] %[Z1] Sloane Square
288791 54=86 [OP] [Z1] Victoria
296794 55=58 [OP] [Z1] St. James's Park
302796 56=34 [OP] [Z1] Westminster
303803 57=03 [OP] [Z1] Embankment
310808 57=73 [OP] [Z1] Temple
316808 58=49 [OP] [Z1] Blackfriars
323809 59=09 [O=vI=] [Z1] Mansion House
325809 59=40 [OP] [Z1] Cannon Street
328808 59=74 [OP] [Z1] Monument
333807 60=24 [OP] (Tower Hill (2))
335807 60=41 [O=vI=] [Z1] Tower Hill (1)
60=78 [-] [Minories Junction]

255795 50.97 [t= t=OI= X] [Z1] High Street Kensington
51.56 [-] [Circle/District boundary (Outer Rail)]
260789 51=8 [-] [Gloucester Road junction]
262788 51=90 [=wO=I=] [Z1] Gloucester Road via Outer Rail

255795 50.97 [t= t=OI= X] [Z1] High Street Kensington
258790 51=51 [-] [Cromwell Curve North Junction]
259789 51=75 [-] [Cromwell Curve East Junction]
262788 51=95 [=OI=OI=] [Z1] Gloucester Road via closed Cromwell Curve
269788 52=67 [=OI=OI=] [Z1] South Kensington via closed Cromwell Curve

The layout for Gloucester Road via the Cromwell Curve is for the date when the curve closed.


Because the service is combined with the Hammersmith & City Line, trains use the same depots.


As described above, almost all of the Circle Line is shared with either the Hammersmith & City Line or the District Line, and a significant portion with the Metropolitan Line. There are thus connections to other portions of each of these lines; all these are flat junctions:

Aldgate Junction Hammersmith & City Line
Baker Street Junction Metropolitan Line
Praed Street Junction Hammersmith & City Line
High Street Kensington District Line
Gloucester Road District Line
Minories Junction District Line

Rolling Stock

The service is normally operated by C stock.

All stock is permitted on the line, with the following exceptions:

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