According to the Evidence Page 26

  AUTHOR’S NOTE

  Though the forensic and legal procedures are broadly correct for 1955, some literary licence has had to be used, both because of the constraints of space and the need to offer an interesting story, as this was intended to be an entertaining novel, not a textbook! For instance, the research into changes into eye fluid potassium has been brought forward a few years, as the first mention was in 1958 and most of the published papers appeared from the 1960s.

  Similarly, the military use of a Thompson sub-machine gun was unusual after the Second World War, though it was employed in Korea and Vietnam and some Special Forces members had an affection for odd weapons.

  Until the highly controversial death of the nurse Helen Smith in Saudi Arabia in 1979, coroners had no obligation to investigate deaths occurring abroad. This has now changed, as the long-delayed inquest into the death of Princess Diana showed.

  The order of court proceedings described at Gloucester Assizes has been manipulated somewhat for the sake of length – the Assizes are now the Crown Courts.

  Agatha Christie’s Mousetrap opened in London on 25 November 1952 – and is still running!