Sir Tom Stoppard uses a recent biography as an "aide memoire" because his memory is so bad he has forgotten details like his grandmother’s maiden name.

Sir Tom, regarded as Britain’s greatest living playwright, worked with the celebrated biographer Dame Hermione Lee on a book about his life which was released last year. 

It was released shortly after the the 83-year-old’s most recent play, a semi-biographical piece called Leopoldstadt, won the Olivier Award for best new play in October.

Speaking alongside Dame Hermione at the Chalke Valley History Festival on Thursday, Sir Tom admitted his memory was sufficiently bad for him to fall back on the book when filling out forms.

Asked whether the biography had ever been an "aide memoire" for him, he said: "On a few occasions since the book was published, I had to turn to Hermione’s book to find out something about myself.

"I would be filling in a form and if it said ‘grandmother’s maiden name’ I’d think: ‘Oh God, I don’t know, what did Hermione write?’, so in a rather trivial way it has been useful.

"The word I use for Hermione’s book in respect of my sense of it, I would say to her: ‘I’m sorry, but your book is radioactive as far as I’m concerned,’ so I haven’t really got into the book in a way a normal reader would open it and read it and so forth. I have read many books since Hermione’s book was published – but not hers."

Dame Hermione Lee and Sir Tom Stoppard at the Chalke Valley History Festival

Credit: Russell Emm/Nature Pictures

Reflecting on a career in theatre stretching back to the 1960s, which has seen him win four Tony Awards, Sir Tom said it was only in his most recent play that he directly grappled with his own past.

Born in the former Czechoslovakia in 1937, his family fled to Singapore following the Nazi occupation until his father died as a Japanese prisoner of war. He arrived in England at the age of eight and grew to consider himself as an Englishman, with his surname taken from his new stepfather. 

It was not until decades later that he became more closely acquainted with his Jewish heritage and learnt that his four grandparents had been murdered in Nazi concentration camps.

Leopoldstadt is set in Vienna in the early 20th century and focuses on the Jewish community of the time. Sir Tom said one character in the play was meant to reflect him at the age of 23, but thought to write it about a Czech family would be too explicitly autobiographical. 

He continued: "What happened to me is that, for quite a few years, I thought of my life as being a charmed life until someone pointed out to me that there was another way of looking at the way I lived which was sort of an escapist life. This whole thing of ‘don’t look back’ of my mother had in a sense betrayed the family I belonged to, many of whom were murdered. 

"In the end I was thinking of how to deal with it and I invented an Austrian family, the only person who was like me was the person who got out in 1938 and ended up in England. 

"There were certain things that I knew what this character would be accused of in public, it was a story I wanted to tell where I arrived at these few minutes when a Holocaust survivor gets through to this English young man and says: ‘Nobody’s life begins at the age of eight.’"

Asked by Dame Hermione why it had taken him a lifetime to write about his personal history, he said: "I’m tempted to say that although I don’t know why I’m rather glad I waited, because my personal feeling is that once I’d written this play eopoldstadt I wasn’t sure there was anything that I would to write about again after this.

"It would have been a shame for me if it had been after my fourth play."