In the 1950s, public support for the death penalty was high. Many believed it acted as a deterrent to criminals, although there was little evidence to support this.

But after a number of high profile miscarriages of justice, most notably the executions of Timothy Evans and Derek Bentley, public support for abolition grew and in 1965, the Labour MP Sydney Silverman, who had committed himself to the cause of abolition for more than 20 years, introduced a private member’s bill to suspend the death penalty, which was passed on a free vote in the House of Commons by 200 votes to 98. The bill was subsequently passed by the House of Lords by 204 votes to 104.

Of the 98 MPs who voted against the bill, one was south west Hertfordshire MP Gilbert Longden. He sat through the seven-hour debate on Silverman’s bill in the hope of catching the Speaker’s eye, to explain why he had voted that way.

He was out of luck – so instead he sent to the Watford Observer a copy of the speech he had hoped to make, in order that his constituents should know his views.

Mr Longden said everything he had learned about human nature prompted him firmly to believe most potential murderers were more likely to be deterred from committing the crime by the prospect of being executed if they are caught.

“I do not believe,” he is quoted as saying, “that imprisonment for life (which means in practice for nine or ten years) is so powerful a deterrent – simply because the optimism inherent in most of us whispers that while there’s life, there’s hope.”

Mr Longden admitted this was a matter of opinion. But, he said: “this House [the House of Commons] evidently took that view [that the death penalty deters criminals] when it passed the Homicide Act of 1957, because that retained capital punishment for some murders, for example that of a warder or policeman.”

He continued: “That act was a compromise which has given rise to many anomalies but I supported it because it relieved judges from the mandatory duty of putting on the black cap in many cases where no one would have wished the convicted person to hang, and it relieved the Home Secretary of having to go through the motions of recommending a reprieve in such cases. I would not extend it to all murders.”

Mr Longden said “eight out of ten” convicted murderers did not deserve to hang.

“But,” he said, “two out of ten are brutal thugs who are better out of this world and only maudlin sentimentality, which is so prevalent in high places today and which is impeding so gravely society’s ceaseless war against delinquency and crime, would keep them alive.”

He continued: “I ask the all-important question of the supporters of this Bill: what is to prevent a thug from carrying firearms and from using them if he knows if he robs with violence he is liable to get 14 years, a sentence which is not subject to reduction at a home secretary’s discretion; while if he kills either a single policeman who is trying to arrest him, or a single witness of his crime, he is liable only to ‘life’ imprisonment, which he knows... in practice means only nine or ten years in jail?

“I conclude by repeating that this grave issue must rest upon personal opinion. But mine is considered and clear. It is that if I were to vote FOR this bill, I should regard myself as an accessory before the fact of many a future murder.”