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?

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.

Over the course of the battle against colonial Britain in Kenya, over 70,000 Africans are believed to have died. 32 white European civilians were killed.