Despite the title Pierrepoint was not Britain's last hangman. He retired in the mid 1950s, shortly after executing Ruth Ellis. Britain never had a "last hangman", as the last two executions before suspension of capital punishment were carried out in different cities at the same time. The last two people executed were both guilty of the murder of John West, so it was decided to carry out the sentence at the same time in Aug 1964. People were still being sentenced to death In November 1965.
As per the promo material, and the DVD insert, this film is "based on a true story," however, it might be more appropriate to describe the film as "based on true events," since the story is rather liberal with the actual facts of Pierrepont's, and other character's lives and circumstances. Big picture, true, small picture, not terribly accurate or precise.
At her execution, Irma Grese tells Pierrepont softly "Schnell" (quickly). This is accurate: according to witnesses and Pierrepont's own memoirs, those were Grese's last words.
The first woman executed in the film, Dorothea Waddingham, was hanged at Winson Green Prison in Birmingham, not Pentonville. Albert Pierrepoint was only the assistant (his Uncle Thomas actually carried out the sentence)
As was customary, prisoners in the film are shown wearing their own clothes rather than a prison uniform.