Which real-life spy is a character in the play 'A Question of Attribution'?

A Question of Attribution is a 1988 one-act stage play, written by Alan Bennett. It was premièred at the National Theatre, London in December 1988, along with the stage version of An Englishman Abroad. The two plays are collectively called Single Spies.

The one-act play formed the basis of a 1991 television film of the same name broadcast as part of the BBC's Screen One series. The film was directed by John Schlesinger and stars James Fox as Anthony Blunt, David Calder as Chubb, an MI5 officer, and Prunella Scales as 'H.M.Q.' (Queen Elizabeth II). The film was produced by long-time Bennett collaborator Innes Lloyd, and is dedicated to his memory.

The New York Times called the film a "razor-sharp psychological melodrama" and it won the 1992 BAFTA TV award for Best Single Drama. Prunella Scales was nominated for Best Actress.

The play and subsequent film is based on Anthony Blunt's role in the Cambridge Spy Ring and, as Surveyor of the Queen's Pictures, personal art advisor to Queen Elizabeth II. It portrays his interrogation by MI5 officers, his work researching and conserving art works, his work at the Courtauld Institute, and his acquaintance with the Queen. Bennett described the piece as an "inquiry in which the circumstances are imaginary but the pictures are real."