THE timing could hardly be worse.

Britain is welcoming athletes from across the world, including many from our former colonies, for the imminent Olympics. At the same time an embarrassing trial has started in London. In it three Kenyans are claiming they were tortured by the British colonial authorities during the protracted 1950s Mau Mau uprising. This could be a most shaming case.

Much was covered up in Britain's imperial past, particularly in the dying years of the empire. It is embarrassing that evidence of atrocities, torture and duplicity is only now being held up to general scrutiny. Something needs to be done to try, even at this late hour, to purge all the wrong that was done.

A statement of sincere contrition from the Prime Minister would not come amiss. The finest hour of his premiership came early on when he responded correctly and graciously to the devastating Saville report on the events of "Bloody Sunday" in Londonderry in 1972. Mr Cameron said sorry, and he said it well. Now we need a generalised, carefully-worded apology covering all the crimes committed by the British and their agents in the problematic years that marked the end of empire. This would not be to prejudge the outcome of any particular legal cases, but it would be seen as a gesture of belated atonement for much that undoubtedly happened and should never have happened.

In the slightly longer term there is an opportunity for deeper and more consistent reflection on these matters. Next year marks the 100th anniversary of the birth of the man who is my greatest political hero. Iain Macleod, the Scot who was Colonial Secretary from 1959 to 1961, was not a typical Tory. He was once a professional gambler (he was a brilliant player of both poker and bridge) and was regarded by many in his party as too liberal, too raffish, and in the notorious words of one Tory dinosaur, "too clever by half".

As soon as he entered the old Colonial Office, Mr Macleod ordered swift and systematic policy reversal. He could not undo the wrongs of the past, but he could decolonise with determination, and this was exactly what he did. He set about dismantling Britain's African empire, no less. Needless to say, this made him desperately unpopular, and not just in his own party.

In Kenya, he moved rapidly to release around 2500 prisoners who had allegedly been involved in the protracted Mau Mau insurrection. Dramatically, he ordered the release of Jomo Kenyatta, the charismatic founding father of Kenyan nationalism and leader of the dominant tribe.

There were around 60,000 Europeans in Kenya. A few were liberally inclined, but many were backwoodsmen, who could not understand that the British Government – let alone the Kenyans themselves – had any right to change things. Many of the white settlers had not reckoned on a radical, decolonising Tory Minister, and were furious when Iain Macleod embarked on his just and necessary work with vigour.

The centenary of Mr Macleod's birth next year gives the chance for a major celebration of his legacy. At least one British statesman responded with vision to legitimate African demands. An assessment of his career could provide a reflective and contrite assessment of what was done, good and bad, in this country's name. Iain Macleod had an acute understanding that Britain could not cling on to its mixed imperial heritage. This was the obvious lesson of the Suez debacle of 1956.

To be fair, he had the support of the prime minister who appointed him, Harold Macmillan. In Cape Town in 1960 Mr Macmillan declared in a magnificent speech that a "Wind of change is blowing through this continent, whether we like it or not". Unfortunately, too many both at home and in the remaining colonies didn't like it. But the need to decolonise was not just a moral imperative, it was also born of necessity. Britain did not have the economic resources to maintain even the tatters of a world empire.