Question: David Edgar wrote a play based on a book by Gitta Sereny, who was a biographer with what nationality?

Context articles: Albert Speer (play)
Pentecost (play)
Written on the Heart
A Time to Keep
Gitta Sereny
The Prisoner's Dilemma (play)
Said O'Reilly to McNab
Playing with Fire (Edgar play)
Daniel Weyman
Steve Waters

Albert Speer was a 2000 play by the British playwright David Edgar on the life of the Nazi-era architect Albert Speer, based on the book "Albert Speer: His Battle with Truth" by Gitta Sereny.
 It premiered that year at the Lyttelton auditorium of the Royal National Theatre, with the title role played by Alex Jennings and the role of Hitler played by Roger Allam.
Pentecost is a 1994 play by the British playwright David Edgar.
 It is named after the Jewish and Christian festival of Pentecost.
 It is set during the early 1990s and concerns the discovery of a mural in a small church.
 It is part of a trilogy of plays on the theme of negotiation set in Eastern Europe in the aftermath of the fall of the Berlin Wall: the other two plays are "The Shape of the Table" (1990) and "The Prisoner's Dilemma" (2001).
Written on the Heart is a 2011 play by the British playwright David Edgar.
 It was premiered by the Royal Shakespeare Company at the Swan Theatre from 27 October 2011 to 10 March 2012, to mark the four-hundredth anniversary of the King James Bible – it draws its title from the translation of Jeremiah 31.33 in that translation and deals with William Tyndale's and Lancelot Andrewes's involvement in biblical translation.
A Time to Keep is a play written by David Edgar and Stephanie Dale.
Gitta Sereny, CBE (13 March 192114 June 2012) was an Austrian-British biographer, historian, and investigative journalist who came to be known for her interviews and profiles of controversial figures, including Mary Bell, who was convicted in 1968 of killing two children when she herself was a child, and Franz Stangl, the commandant of the Treblinka extermination camp.
The Prisoner's Dilemma is a theatrical drama written by David Edgar.
 It refers to the game theory problem of the same name and portrays its outworking in an Eastern European, post-Cold War setting.
 The play premiered in The Other Place Theatre by the Royal Shakespeare Company in July 2001 and forms part of a trilogy with "The Shape of the Table" and "Pentecost".
Said O'Reilly to McNab is a 1937 British comedy film directed by William Beaudine and starring Will Mahoney, Will Fyffe and Ellis Drake.
 It was made at Islington Studios by Gainsborough Pictures.
 The film's sets were designed by the art director Alex Vetchinsky.
 Leslie Arliss and Marriott Edgar wrote the screenplay.
Playing with Fire is a 2005 play by the British playwright David Edgar, dealing with race relations and multiculturalism.
 It premiered at the Royal National Theatre in 2005, with a cast including David Troughton and Emma Fielding.
He has appeared in stage productions such as Samuel West's Sheffield Crucible production of "As You Like It" (as Jaques) and the Chichester Festival Theatre's production of David Edgar's "The Life and Adventures of Nicholas Nickleby".
 His portrayal of the title character earned him a nomination for 'Best Performance in a Play' at the 2006 TMA Awards.
 He played "Anitpholus of Syracuse" in the "Whatsonstage.com Awards" Best Shakespearean Production nominated "The Comedy of Errors" at the Open Air Theatre, Regent's Park in 2010.
Steve Waters is a British playwright.
 He was born in Coventry, UK.
 He studied English at Oxford University, taught in secondary schools and was a graduate of David Edgar's MA in Playwriting in 1993, a course which he later ran for several years.
 He has written about the pedagogy of playwriting, contributed articles to The Guardian, essays to "The Blackwell Companion to Modern British and Irish Drama" and "The Cambridge Companion to Harold Pinter", and has written a book entitled, "The Secret Life of Plays" (2010).