For their roles the actors immersed themselves in the eighteenth century to get a better understanding of the society and expectations of the time. Keira perhaps had the easier task of the actors as so much of Georgiana's life was documented.
'The current Duchess of Devonshire actually took me into one of the rooms to look at some of Georgiana’s thing, which I could actually look through, which was fantastic.
Her gambling books, which we tried to get into the film but it never quite worked, but she was a huge gambling addict so it was amazing to see her debt books in her own hand and to be able to look through those, and some of the letter as well, so she was wonderfully helpful.'
She continued: 'I think we all though it was necessary to do research, I mean I personally love doing it so it was a wonderful opportunity to just find out about eighteenth century culture and society which I didn’t know about.
Also we had Amanda Foreman on set a lot, which was fantastic, she was always there to answer questions and she was incredibly supportive, sometimes it’s quite terrifying to have the writer there, but she was great.'
But for Atwell and Cooper intimate details about Bess and Earl Grey were not as easy to come by as Hayley explained: 'There was a book called Dearest Bess, it was a novel but it was base on the letters between Bess and Georgiana, and it provided more of an insight into Bess’ background and made her intentions for Georgiana and the Duke a little bit clearer.'
And from Dominic, who has just come from the dance routines of summer hit Mamma Mia the character of Earl Grey gave the actor a chance to delve into the political industry of our country: 'There was a wealth of material on the back of a Twinings tea box, which is where I did my research, no he was a fantastic person to investigate, I wasn’t even aware that he had become Prime Minister, and was PM for four years in this country, so he was a fantastic person to discover and realise what a passionate and young politician he was and how he was able to put everything on the line for the love of his life, that in the end he didn’t get (laughs).
'There wasn’t an archive as such just a lot of information that I could dwell upon, and not use, no there was nothing I had physically that I could use.'
Saul chips in: 'The basic facts of their relationships are documented but what goes on in these private bedrooms and hallways is the stuff of our creative imagining but what we are trying to do is get the essence.'
'I think that’s right,' Keira adds. 'I think fundamentally at some point you have to put the biography away and stick to the script it’s a dramatisation not a documentary so you do have to just tell the story that you are trying to tell and you have to let your own imagination go as well, it’s great to be able to read all these things read their letters and you can kind of mull it all over in the back of your head but fundamentally you have to stick to the script.'
But while the actors were delving into the lives of their characters Georgiana, Bess and Earl Grey do not come from fiction and the Duke of Devonshire line is still very much alive today so what pressures did the cast feel to doing them justice.
'Personally speaking none you are given a job and your job is to make an interpretation of a character in a script or someone who was living and to work hard enough to feel like you are doing it justice, says Atwell.
'If you play someone who had lived there is the risk of imitation or you can focus more on the essence of the character as opposed to physical mannerisms or what is it about this particular adaptation, whether is’s fictional or not, is trying to say.'
'You have to remember that although there is a lot of information it’s largely incomplete and you have to take with a pinch of salt large amounts of the information that you have of those people you just have to trust the performances and the instinct that create the piece of drama that works, adds the director.
But no matter how we look at the film many will still draw the comparisons with Princess Diana and the tag line 'there were three people in her marriage' further adds to the parallels being made.
Dibb explains: 'The reality is there’s the filmmakers, which is all of us making the film, and then there’s marketing afterwards and they are two different things we had the freedom to make our film and they have the freedom to market the film, it cost them a lot of money and they want to get a wide an audience.
'All they have done it made explicit what would have been written by everyone anyway they have just cut out the middle man and gone straight to it. It doesn’t represent us and approach to the film but for them to make that choice is up to them and if it gets more people in to see the film perhaps they are right. It’s just a marketing device.'
And while the synopsis claims that unlike Diana the Duchess found her happiness Keira Knightley strongly disagrees.
'No, and we disagree about this (to Saul) which I think is great, but it’s not my place to dictate I think if you think it’s happy, and some people do actually, then that’s great and if you don’t you don’t.
'I think the whole journey for her is one from idealism into reality in a strange sort of way and she gets broken down the whole think is like a card game and she plays her cards out and for me no she didn’t get a happy ending but she does survive, which in itself I suppose is a happy ending, she gets the children and she chooses and she compromises.
Could she have lived with the guilt if she had gone off with Grey and given up the kids? No I don’t think she could of done. I don’t know about happy ending but she is someone who isn’t brought down by it she survives and that can only be positive.'
The Duchess is released 5th September
FemaleFirst Helen Earnshaw
Read the The Duchess Interview Part 2