Having a ball! Cressida Bonas is whirled around the dance floor in an elegant period dress as she makes her TV debut in lavish costume drama Doctor Thorne 

With her charming grace and flowing ball gown, she certainly looks every inch the aristocrat.

But then, Cressida Bonas has had her fair share of practice attending such regal events as featured in ITV's Doctor Thorne.

Prince Harry's former girlfriend makes her television debut on Sunday in the three-part drama that sees her play the small part of Patience Oriel, a ‘very pretty’ potential love interest for a main character who is dismissed because her fortune is not big enough.

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Cressida Bonas, 26, is set to make her television debut with Doctor Thorne, which airs on ITV this Sunday

But this does not stop her from dancing with him in an impressive ballroom scene that sees her twist and turn with all the assurance of an experienced social butterfly.

Based on the 1858 novel by Anthony Trollope, Doctor Thorne has been adapted for the screen by Downton Abbey creator Julian Fellowes and has already been dubbed the ‘new Downton’.

However, despite its country house setting and aristocratic intrigue, it is a label the writer has been keen to shake off.

He said at an advanced screening of the first episode: ‘It worries me slightly when I see Doctor Throne called the new Downton because it isn’t.

‘It’s a little piece, a little three parter, a love story for spring to enjoy with a bottle of wine and then cry at the end. It’s a smaller thing and I love that kind of television.

‘I don’t want people to think this is the new Downton and that we’ll still be here in seven years’ time because we just won’t.’

Cressida, far right, looked every inch the experienced social butterfly as she donned a traditional ballgown

The starlet can be seen making her way around the ballroom with co-star Harry Richardson

Miss Bonas broke up with Prince Harry in 2014 after a two-year relationship and at one point was tipped to be his bride.

She has since been trying to break through as an actress and is being championed by movie mogul Harvey Weinstein, who produced the BBC's adaptation of War And Peace and Doctor Thorne.

She will also make her Hollywood debut in his film Tulip Fever this year alongside Judi Dench, Alicia Vikander and Cara Delevingne.

In Doctor Thorne, she stars alongside War and Peace actress Rebecca Front and Tom Hollander, who plays the title character.

Hollander, 48, also have the key role of an arms dealer in BBC One’s spy thriller The Night Manager that is Doctor Thorne’s direct competitor in the primetime Sunday evening slot.

It is not often that actors find their projects facing off against each other, especially in such high-profile series. But the actor, known for comedy Rev, refused to be drawn on which he would like to see win the scuffle.

New venture: The period drama - her TV/film debut - is set for a 2016 release and is being produced by Hat Trick Productions

He said catch up services mean no one has to miss either, explaining: ‘The internet will save anybody from the crisis you are describing, it will be alright.’

Fellowes added that ITV’s frequent advert breaks puts Doctor Thorne at a disadvantage against the BBC’s John le Carre adaptation.

He said: ‘This thing of them going out together, it will affect the ratings that are marked down but it won’t affect who watches the show because we’ll just watch it an hour later or we’ll go onto iPlayer or we’ll go onto Netflix. If we want to see it, we’ll see it.

‘In a way, recording us means they can go whizzing through the commercials while in The Night Manager there are no commercials so in reality, that way round probably doesn’t work too well in our favour.’

The Night Manager, which is based on the novel by John Le Carre, is already two episodes into the series and enjoys audiences upwards of six millions, provide a tough challenge for Doctor Thorne to meet.  

Small-screen actress: Winchester-born Cressida is set to play a character called Patience Oriel

Cressida was first spotted filming on-set for the period show in November, alongside her co-stars. 

Despite the fact that it is to be her first filmed acting role, Cressida seemed unfazed as she laughed and giggled on-set. 

Her blonde tresses were styled in pigtails tied up with multi-coloured ribbon, while she sported little make-up.

Cressida donned full period dress for the scenes, wearing a puff-sleeved ballgown in pastel hues.

The bold frock cinched in at the waist, and featured a full, voluminous skirt, to highlight her figure.

But it mustn't have been a warm day as she was seen wrapping up in a black bomber jacket.

A day's filming must have also made the British actress rather hungry as she was seen sipping from a cup of tea and nibbling on a biscuit.