The Duke of Rutland can fly the flag above Belvoir Castle again thanks to the skills of a helicopter crew.
They came to the rescue after the original flag pole was broken by fierce winds in February last year.
Cellars and other voids around the turreted stately home of the Manners family meant they could not use a crane.
That is when the insurers chartered a Bell Huey helicopter to fly to the rescue.
But they had to wait for the wind to die down before lifting the 36ft tall pole into place on the roof of the castle's south-east turret.
The operation took 45 minutes to complete on Thursday.
Church and heritage claims director from Ecclesiastical insurance Andrew Brown said: "This was a unique challenge for us. As a specialist heritage insurer, we've been called upon to repair many of Britain's finest buildings.
"But this is the first time we've needed to fly the flag quite so literally."
He said a helicopter had to be used because cellars and voids underground meant that a crane could not be positioned close to the castle to hoist a new pole into place.
Scaffolding was also ruled out because of the risk of damaging building's roof.
He added: "The potential for down-draft from the helicopter to damage the roof was also a serious consideration in the operation."
He said the helicopter lifted the flagpole vertically from a spot close to the castle and flew it over the roof, from where a specialist team were able to reach the bottom of the new pole and secure it to the undamaged lower half of the pole.
Mr Brown added: "It was always going to be touch and go whether we'd get the green light for the operation.
"Carrying such a large, heavy flagpole vertically would have been dangerous if the wind speed had exceeded 10 knots."
The replacement flagpole was made by Bristol Wooden Flagpoles and then transported by road to the Vale of Belvoir.
It is made of the finest marine grade Sitka spruce and took a month to shape by hand.
The insurance company also oversaw the production of a stainless steel bracket 1.8 metres high and weighing 120kg to secure the new pole to the base of the old one.