Criminalisation begins...

A piece from Past2Present 2010 by Beth Brook

The first legislation against homosexuality in England was introduced to Parliament in 1533  by Thomas Cromwell under the reign of King Henry VIII. This was The Buggery Act, which defined the offence as committed with man or beast and was the first criminalisation of homosexual activities.
It is sometimes suggested that the Act was introduced as a measure against the clergy, since the Act was introduced following the separation of the Church of England from Rome, though there seems to be no firm evidence for this. The Act itself only states that there was no "sufficient and condigne punyshment" for such acts. The Act was, however, repealed in 1553 on the accession of Queen Mary and then re-enacted by Queen Elizabeth I in 1563.
Buggery remained a capital offence in England and Wales until the enactment of the Offences against the Person Act 1861 (under section 61, ‘Unnatural Offences’):
Whosoever shall be convicted of the abominable Crime of Buggery, committed either with Mankind or with any Animal, shall be liable, at the Discretion of the Court, to be kept in Penal Servitude for Life or for any Term not less than Ten Years.
The Penal Servitude Act 1891 abolished the minimum penalty for the crime of sodomy.
Parliament finally repealed buggery laws for England and Wales with the Sexual Offences Act 1967 (at least insofar as they related to consensual homosexual acts in private), ten years after the Report of the Departmental Committee on Homosexual Offences and Prostitution, better known as the Wolfenden Report, in 1957.

The First Execution for buggery, along with treason, was of Walter Hungerford, 1st Baron Hungerford of Heytesbury, although it was probably the treason that cost him his life. Nicholas Udall, a cleric, playwright and Headmaster of Eton College, was the first to be charged with violation of the Act alone in 1541, for sexually abusing his pupils. In his case, the sentence was commuted to imprisonment and he was released in less than a year.
The last execution, on 17 November 1835, was of James Pratt and John Smith, two poor, married men caught in the act in a run-down boarding house in Southwark. Their appeals for clemency were rejected and they were hanged together before a crowd that was ‘excessive, but exceedingly decorous’, according to The Times.
Sources: www.wikipedia.org; pp109-110, A Gay History of Great Britain, ed. by Matt Cook

The last executions in the UK, by hanging, were in 1964, prior to capital punishment being abolished for murder in 1969 in Great Britain and in 1973 in Northern Ireland. Although not applied, the death penalty remained for some other offences until 1998.
The last death sentence in the UK was imposed on  William Holden in 1973 in Northern Ireland, for the capital murder of a British soldier during the Troubles. Holden was removed from the death cell in May 1973.
The last civilian offences punishable by death were treason and piracy with violence, the death penalty was abolished for these by the Crime and Disorder Act 1998.

Consequences...
Even after the death penalty was removed, the social consequences could be appalling:-
On 21 November 1891, at Newcastle Assizes (what is now known as the Crown Court), George Canham (28) and M Baker (31) were convicted of sodomy with each other and both sentenced by Judge Wills to 10 years penal servitude.
Baker committed suicide by taking poison in the police cell passage immediately after sentence.
National Archives file HO 144/243 Bestiality - Reduction of sentence of penal servitude