Stephen Fry admits the one thing 'I will never do' as an actor in brutal comparison to Christian Bale

The 66-year-old had to learn Polish for the role and told Radio Times: "Well, I wouldn’t want to claim that I am now fluent! But I learnt the speeches in the script, the structure of the language and the pronunciation of the different diphthongs and triphthongs that Polish has."

He went on to discuss the one thing he wouldn't do and revealed: "Well, I’ve read about certain things that actors I admire do, that I will never do. For example, lose staggering amounts of weight, like Christian Bale."

Speaking of what audiences could expect from the film, Fry told the British Film Institute: "The strongest links we have are the links of father-daughter, mother-daughter and mother-father. Those are the ones that you rely on.

"Poor Ruthie’s emotional life is totally broken with Garth, her husband, and the relationship with her father. And [she has] never really spoken properly to her mother about her traumas. What really brings them together is not history.

"History can’t make restitution in that way. Only two people talking to each other can. So it is a human film. It’s not about being a Jew, being a victim of Nazism or the Holocaust itself. That’s the lens through which you look at something as primal as a father-daughter relationship."

His new movie and recent admission comes after he had to apologise after making an inappropriate comment towards the Marylebone Cricket Club - saying the image was one of "beetroot-coloured gentlemen".

During his recent appearance at the Hay Festival earlier this month, The Kingdom star spoke disparagingly of the MMC’s public image and told the audience: "MCC has a public face that is deeply disturbing.

"Beetroot-coloured gentlemen in yellow-and-orange blazers sitting in front of the Long Room and looking as if they’d come out of an Edwardian cartoon.”

Whilst speaking on a panel with Azeem Rafiq, the former Yorkshire cricketer, about racism and a lack of diversity in cricket, he added that such an image was not a “fair face to see of the MCC”.

However, it was reported that a number of members had written to the club furious with the comments made by Fry, forcing him to release a statement apologising.

In an email posted on the members’ independent forum, The Times reported it said: “Oh dear, I’ve made a complete clot of myself yet again. I’m so sorry that what I said at Hay has come across as criticism of the club, its members, and its ethos - I was attempting the exact opposite.

“I went off into a wildly overdone - absolutely - prose picture of the image that some have of the club. Edwardian, public school, etc etc. Very much, I admitted ruefully, my image too.

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“Yes, I should have made it clearer that the reality is different, but I thought I had and that it was obvious.”

He added: “I didn’t really get time to make the case for the club as clearly as I should have. What came across is the opposite of what I wanted to say.

"I cannot apologise enough for my stupidity. I should have known better. But please be assured that I love, honour, value, respect and admire this wonderful club of ours.

"I am proud to think of all it does for cricket and I curse myself for the recent flurry of attention I have caused. All I seemed to do was to pick at a scab that was already healing. I am truly so very sorry.”