Lydia Leonard, who plays Anne Boleyn in the stage adaptation of Hilary Mantel's books Wolf Hall and Bring Up the Bodies, wears a necklace given to her by Mantel for every performance. The fake "B" gold-and-pearl necklace, which Leonard describes as "something you get in a toy shop or from The Tower of London gift shop", is an exact replica of Anne Boleyn's famous B necklace, which she wears in many of her portraits.
Leonard was given the piece of toy jewellery by Mantel during rehearsals for the Royal Shakespeare Company production, which opened in Stratford-upon-Avon earlier this year and which is now transferring to London's West End.
"It's a lovely necklace Hilary gave me," says Leonard. "Somebody gave it to Hilary, but she wanted me to have it. You could get it in a tourist place, but it is rather nice. Betty Suarez also wears the same replica in Ugly Betty. It's quite ghetto in a way."
According to Leonard, the Man Booker prize-winning author Mantel, who won the award for both Wolf Hall and Bring Up the Bodies, is on tap to answer any questions via email, night and day. "She has lots of incredible advice and support because she has spent so much time inside Anne's mind herself. She once told me she knows what an occasionally dark place it can be," says Leonard, who finds it easier to switch off from her character when she gets home than she did at the beginning of the run.
"Especially in the second part, Bring Up the Bodies, Anne is very tightly wound physically. Her nerves are frayed because of the pressure she is under and the tide is turning. In my mind, none of the charges were true that were put against her. A woman who can say "no" to the King of England and keep saying it for six years, doesn't strike me as a women who is going to jump into bed with all his friends."
But Mantel is always there for Leonard to seek clarification about her character as Henry VIII's second wife. She has been in rehearsals a lot of the time but if she's not there, Leonard will ping her an email.
"Hilary can tell you what Anne Boleyn is thinking at any given moment – she can be so specific and deep," says Leonard. "Hilary is right here; she knows those characters so well. She really has inhabited them for many years."
Although many people will opt to see Wolf Hall and Bring Up the Bodies in two parts, because they are each three hours long, twice a week the company do both parts in one day. "It doesn't feel like six hours though," says Leonard. "In Stratford, we occasionally had to do them the wrong way round, but in London they will be in the proper order. It is satisfying telling the whole story at once, particularly for me as Anne Boleyn, because it's all about her rise and fall."
Mantels' epic books about the political ascent to power of Thomas Cromwell, which were adapted for the stage by Mike Poulton, have been met with critical and public acclaim. Many of the RSC company will transfer to the West End with Leonard, including Ben Miles as Cromwell, Nathaniel Parker as Henry VIII, Paul Jesson as Cardinal Wolsey and Lucy Briers as Catherine of Aragon. Mantel's books have sold 1.8 million copies in the UK and this production is a sure to be a box-office hit, as it was in Stratford-upon-Avon.
Leonard hopes she is "serving" Mantel's story in her portrayal of Anne Boleyn – "not much is known about her for such a public figure because a lot of it was destroyed by Henry VIII after she died".
She adds: "There is so much rumour because while she was alive she was the focus of every lurid story the imagination of Europe could dream up. Picking that apart, I am very much playing Hilary Mantel's Anne Boleyn. The relationship between Anne and Cromwell is fascinating,"
The British actress Leonard, 32, who was born in Paris and lived in France until she was five years old, trained at the Bristol Old Vic Theatre School. Her professional debut was as Polyxena in the RSC production of Hecuba in 2005, starring Vanessa Redgrave. Then in 2006 she was cast as Caroline Cushing in the original Donmar Theatre and West End productions of Frost/Nixon. She played Hazel Conway alongside Francesca Annis in the National Theatre's production of Time and the Conways in 2009. In 2010, she played Jackie Onassis in Martin Sherman's play Onassis at the Novello Theatre in London.
She starred in Joanna Hogg's 2011 feature film, Archipelago, opposite Tom Hiddleston, in the story about a fractured family on holiday in the Isles of Scilly. She also appeared on TV in BBC2's Ambassadors at the end of last year, the comedy starring David Mitchell and Robert Webb as two hapless British diplomats in the fictional republic of Tazbekistan.
But this is Leonard's most major role to date; she has 11 costumes for her as Anne Boleyn, made by the RSC costume department. "Anne Boleyn is certainly the most exciting character I have played on stage. To have Hilary to fall back on, who is such a font of knowledge, is such a gift while playing this role."
'Wolf Hall' and 'Bring Up the Bodies', Aldwych Theatre, London WC2 (wolfhall.co.uk) 17 May to 6 September