In 1965, capital punishment for murder was temporarily abolished in all countries of the U.K. but for Northern Ireland. In the 1990s, all forms of capital punishment in the UK were ended, not that they had been used since 1964. Abolition in 1965 was motivated by a number of factors: public opinion as a result of high profile cases of execution, long-term pressure groups, individual politicians' actions, the failure of the 1957 Act which governed the conditions under which the death penalty could be given, and the liberalisation and globalisation of British society, as well as the failures of the retentionist movements. Although pressure groups and public action was significant in the abolition of the death penalty, it should also be noted that the vast majority of the British public did not support abolition in 1965, however there was nonetheless significant public outcry by vocal abolitionists, with changing voting patterns allowing for more liberal MPs, who were ultimately to allow for the abolition. In 1998, when complete and formal abolition occurred, it was much more simple: it was part and parcel of a significant and beneficial ruling and agreement, and was of little apparent significance in the minds of both the general public and politicians as a result of the death penalty having been de facto defunct for decades, with the change to de jure being much easier, with the last executions in the UK all occurring before 1964, and the last sentence of death in the entirety of the UK being in 1973 in Northern Ireland, which was not carried out.

Long before 1965, there had been opposition to the death penalty. Notably, William the Conqueror had an apparent aversion to the use of the death penalty outside of political and military punishment or execution, despite having a deservedly bloody reputation. However this was not a formal or ideological position, with the idea of abolition only becoming a reality following the Enlightenment, although a distaste for capital punishment was not reserved for the philosophers and intellectuals by any means, with ordinary people being often hesitant to prosecute for fears of the defendant being executed, and juries often undercharging or under sentencing in order to avoid the use of the death penalty, throughout the 18th and early 19th century, when the use of capital punishment was particularly common.

Abolition in the UK was strongly influenced by continental concerns. It was the French who initially led the way for people such as Samuel Romilly, an MP and Solicitor General, who repeatedly sought to lessen the use of capital punishment and succeeded in reducing the compulsory sentences for several minor crimes which previously would have resulted in the death penalty, in the early 19th century. He was not an abolitionist, but he evidently was deeply concerned about the use of the death penalty and was a reformer of the death penalty, and therefore a notable figure in abolitionist history. However these proto- or semi-abolitionists were strongly influenced by people such as Montesquieu who shared similar views to Romilly in desiring the reduction and mitigation of the use of the death penalty. Aside from Montesquieu, there were greats such as Cesare Baccaria, an Italian author who's publications convinced many notable figures to support total abolition. In the 19th century, both Portugal and San Marino abolished or stopped using the death penalty. Outside of Europe, multiple Latin American countries, such as Venezuela and Ecuador, also ended the use of capital punishment.

By the start of the 20th century, the world of the death penalty has changed dramatically, with its usage being extremely limited: murder, espionage, certain forms of arson and violent piracy, as an example. Following the 306 British and Commonwealth soldiers executed in the First World War, with multiple cases of people who were not subject to the proper medical examinations or investigations to diagnose, for example, shell shock, politicians became more active in regards to the death penalty, although the public did not, reducing the use of the death penalty in a military context to treason and treachery in 1930, this same year, a commission recommended the abolition of the death penalty, although it was ignored.

Aside from fears over miscarriages of justice and failed legal process, there was also growing concern over the subjects of the death penalty, regardless of context and crime. The late 19th and early 20th century saw the end of the use of the death penalty for minors, the last person under the age of eighteen was executed in 1889, and a 1908 act formally abolished the use of the death penalty for those under the age of sixteen, and in 1933, the death penalty was abolished for those under the age of eighteen. This was important in the abolition of the death penalty because it showed a moral concern for those who underwent capital punishment regardless of their crime, when previous efforts under UK law involved reserving capital punishment for only certain heinous crimes, or for ensuring that capital punishment could only follow fair legal processes. This was an important step as it was essentially a moral stand, it was not about the death penalty being ineffective, it was not about the death penalty not being suitable for a crime due to the crime itself not being 'bad' enough, it was not due to injustice in what had led to the death penalty sentence, it was about the usage of the death penalty itself, and saying that for certain people, regardless of how horrible their crimes, regardless of how fair their trial, regardless of any further context, the death penalty was immoral.

Following the war, during which capital punishment had been used in certain, generally well supported, circumstances, the modern abolition movement in the UK truly began, and not as a public movement. In the 18th century, abolition was an intellectual and philosophical domain although the general public itself tended towards a mild aversion to the use of the death penalty in many cases- but not supporting abolition in general at all-, and in the 19th century, it became a media and middle class morality-driven cause, supported by the law, with the ending of public executions being significantly as a result of media outcry against the perceived chaos which surrounded public executions, and concerns over the moral effects of witnessing executions. In the early 20th century, and up until much of the mid 20th century, in many ways public support for abolition lagged far behind political and legal official support. In 1925, the National Council for the Abolition of the Death Penalty (NCADP) was founded, campaigning to end capital punishment. Initially it achieved very little. In 1927, multiple Labour Party members created a manifesto advocating for the abolition of the death penalty, but there was very little public support for such a thing.

In 1945, an entirely new generation of MPs were elected, many of whom had witnessed death first hand in the war, or who were more liberal and continental-leaning than predecessors. Abolition had never truly been on the political agenda beforehand- although reduction in the use of the death penalty certainly had been- and although there were abolitionists, at this point, even for politicians, the death penalty was seen as a simple fact of life, with the 1927 manifesto mentioned earlier being limited in scope, as although Labour was abolitionist, this did not entail cross party support or out of party support, the NCADP being very small and the special commission of 1930 being ignored completely. However there were indeed prominent abolitionists and initially, individuals were the key driving factor in abolition. This is not a Great Man theory of abolition, however it did take Sydney Silverman to the issue of abolition onto the agenda of Parliament. Once it was there, there was significant and widespread political support, however until then, it had simply not been thought of or raised.

Sydney Silverman was born in 1895, and can perhaps be credited as the person who initiated the modern abolitionist movement in the UK which culminated with the temporary 1965 abolition of the death penalty, which was later confirmed as permanent. He was born into poverty, in an area with a high crime rate, and as a result, an area which had experience with the use of the death penalty. He did not serve in WW1, being a conscientious objector, and this pacifism (this changed during the Second World War) motivated his desire for abolition, as well as exposing him to the inside of the justice system which undoubtedly formed his political aims and specific focus on the death penalty, and not other likely and similar causes, supported by his study of law. Following the failure of both the Royal Commission and the Criminal Justice Bill, Silverman and Victor Gollancz created the National Campaign for the Abolition of Capital Punishment (NCACP) in 1955, by this time the NCADP had ceased to exist and had become part of the Howard League for Penal Reform, which still exists today.