In September 2009, the then prime minister Gordon Brown issued an apology for the British government's mistreatment of computer scientist Alan Turing. Turing was persecuted for his homosexuality in the aftermath of WWII, which he helped win by inventing the modern computer for the Allies, allowing them to crack Nazi military codes. He was institutionalised and subjected chemical castration.
There was certainly some public support for an apology. A petition on the Downing Street website had raised thousands of signatures. But there was an interesting contrast: a few months earlier the Conservative Party and some of the media had asked Brown to say sorry for something that his government had actually done. Brown had refused to apologise for an attempt by his adviser Damian McBride to smear senior Tories.
Brown has form apologising for things that he didn't do — he also said sorry for Britain's heinous policy of forced deportation of children to Australia. But he is certainly not the only politician to have preferred to apologise for the sins of others than his own.
One of the most emotional apologies to be made by a politician in recent times came from Livingstone. As Mayor of London he apologised for the city's role in the Atlantic slave trade, which ended some 200 years ago. The former mayor actually broke down in tears during his sombre speech. But a year earlier Ken was suspended from office for a poorly-judged comment he made about a Jewish reporter, a transgression he repeatedly refused to apologise for, prolonging the episode.
Cameron apologised for the Tories' notorious Section 28 legislation, passed by the Margaret Thatcher government while Michael Howard was home secretary. The law banned the "promotion of homosexuality" in schools. But in a 2010 interview with Gay Times, he stood by a decision to allow Tory MEPs to vote against gay equality measures, looking visibly flustered when questioned further.
An apology for a historical wrong is different to saying sorry while in office. Reacting to their own shortcomings or mistakes can be a negative admission for a politician, and falling poll ratings can follow. But saying sorry for a wider problem that isn't necessarily the fault of the politician shows sensitivity and an awareness of public sentiment on a certain issue. Get this right, and it can actually be beneficial.