According to the commentary by Sir John Hurt on the DVD, real-life retired executioner, Albert Pierrepoint, was a Technical Advisor for the execution scene. This scene was the first British people had seen in a cinema of a British hanging, and as it was still covered under the government's Official Secrets Act, no details regarding the scene were available. This is where Pierrepoint came in, under an assumed name, and was able to re-create the harrowing scene to maximize the true terror of what it must have been like.
Sir Richard Attenborough once said of playing John Christie in this film in an interview with "The Times" of London on May 18, 1970: "I do not like playing the part, but I accepted it at once without seeing the script. I have never felt so totally involved in any part as this. It is a most devastating statement on capital punishment."
The film was nominated for a BAFTA Award for Best Supporting Actor for Sir John Hurt. The nomination was Hurt's first BAFTA nomination (he did not win), with several others following in his career, with Hurt winning a BAFTA next time for Best Actor in a television role for his part in The Naked Civil Servant (1975).
One of the dust jackets from Ludovic Kennedy's source book described the story of the Rillington Strangler as follows: "The horrifying and incredible true story of John Reginald Halliday Christie, the necrophile who strangled, and then made love to seven women. This is the case that rocked England and the entire civilized world."
The movie's closing epilogue states: "Christie confessed his crimes and was hanged at Pentonville Prison. Twelve years later, Timothy John Evans was pardoned, his body exhumed and reburied in consecrated ground."
The trivia items below may give away important plot points.
Wrongly considered as a goof: When Beryl's body is discovered, the police cut the cords and her legs extend. Some felt rigor mortis would prevent her legs from straightening. However, rigor mortis does not last. It sets in after two hours or so and the body continues to stiffen for 8-12 hours. It remains in the most rigid state for up to 18 hours, depending on the temperature. After that, the body relaxes again. In humans, it is generally over within 48-60 hours after death. The following events take place between the murder and the discovery of the boy by the police: Between the murder and the police discovering the body, 1. Evans leaves London and takes train to his relatives in Wales. 2. "On Monday," his relatives send a letter " to Beryl's father in Brighton. 3. They receive a telegram from Beryl's father in answer. 4. Evans decides to confess, telling police he can't keep it to himself anymore (implying time has passed since the murder), but says he put the body in the drain. 5. The police go to search the drain. Find nothing. 6. The police come back to station and question him again. 7. Police return to 10 Rillington place and finally find the body. Four to five days could easily have passed during these events. There seems to be plenty of time for rigor mortis to have left, and so Beryl's legs would straighten out when the cord is cut.
Sir Richard Attenborough portrayed the central character of real-life serial strangler John Christie in this film. Attenborough had played Detective Sergeant Trotter on London's West End stage production of Agatha Christie's "The Mousetrap", who it is revealed to be the killer. The real-life strangler, and the writer of the latter, both shared the last name of "Christie".