The vote on same-sex marriage went 366 in favour to 161 against. That is, approximately two thirds of the House supported the government. The larger part of the one-third opposition was not the Opposition at all; it was the government's own party. In a free vote, the government only got its bill through by doing deals with the party which it nominally opposes.
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.Source: wiki, which goes on to detail the exclusions and parliamentary technique used to present abolition as suspension. The split, again, was a two-thirds for change, one-third for the status quo. Note also in subsequent developments that there was a deadline; the abolition had to be enacted in English law before a European-set deadline. If it had not been done then the authority of European law would have become much more visible to the voting public. As with same sex marriage, the impetus is not from within Britain but to disguise the fact that the real power comes from outside it.
Despite the parliamentary feeling that the argument about the death penalty is done and dusted, no politician would dare put the matter before the public. The public is much less convinced that there is any point in keeping Ian Huntley breathing, and it is about to ask the same question of David McGreavy who has failed in his bid for anonymity. Despite what some people claim, the law does not lead public opinion as much as they would like, nor is it clear that we get good law when it tries to do so.
English law jumps before it is pushed in order to disguise that hand of the pusher.