The past usually finds a way of catching up with us. Could Britain's colonial sins pose a risk to our relationship with the soon-to-be most powerful person on Earth?

According to the Times, Barack Obama's grandfather was imprisoned and tortured by the British during Kenya's Mau Mau uprising.

The claim is spread across three pages of the newspaper and illustrated with black and white photographs of detention camps operated by British soldiers in the 1950s.

Hussein Onyango Obama, the president-elect's paternal grandfather, had served with the British army in Burma during the second world war and later found work back in Kenya as a military cook.

Like many army veterans, he returned to Africa hoping to win greater freedoms. But his aspirations soon turned to resentment of the occupying British.

He became involved in the Mau Mau independence movement and was arrested as early as 1949, probably on charges of membership of a banned organisation.

During two years' detention he was subjected to horrific violence, according to the story's authors, Ben Macintyre and Paul Orengoh. Tortures inflicted on Kenyan prisoners sometimes involved such barbaric implements as "castration pliers".

"The African warders were instructed by the white soldiers to whip him every morning and evening till he confessed," Sarah Onyango, 87, tells the Times.

The behaviour of British soldiers is the subject of continuing legal action in the UK courts from victims seeking reparations for torture and mistreatment suffered more than 50 years ago. The Kenyan Human Rights Commission is still gathering evidence.

The alleged torture of Onyango reportedly left him permanently scarred and bitterly anti-British. Barack Obama's memoirs, the paper observes, show that he too is no admirer of British colonialism.

Obama's family connection to the Mau Mau was already known – some US commentators have even used the label to smear him as a "Mau Mau insurgent".

Obama, with more pressing contemporary problems on his plate, is unlikely to be fixated on extracting revenge from the UK. But he may draw the broader historical conclusion that the imposition of torture and repressive violence has a habit of undermining the political legitimacy of world-class powers.

He has already signalled his determination to close the Guantanamo Bay detention centre and speed up withdrawal from Iraq. We will have to wait and see whether his grandfather's experience has a bearing on his policies on Afghanistan and international terrorism.