London is papered with posters this week to announce today’s concert to celebrate Nelson Mandela’s 90th birthday. A host of musicians are preparing to perform in honour of the old man of South Africa in London’s Hyde Park.

Reading the posters evokes memories of my father, who was 95 when he died a little under two years ago. I think of the span of both men’s lives, including Mandela’s time – 27 years! – in jail. His willingness to face imprisonment in pursuit of equality for black people marks him out, as does his willingness on leaving jail to “get stuck in” to the task of creating a South Africa, post apartheid, that was worth fighting for.

I also think of the loss of Mandela’s son, Makgatho, to AIDS in January 2005. For my father, one of the greatest challenges of old age was the death of loved ones, though never – thankfully -a son. Thinking of Makgatho’s death I think of Bill Gates, retiring this week from the fulltime chairmanship of Microsoft to dedicate more time to the Bill Gates Foundation. Gates’ commitment through the work of the Foundation to the health of some of the most disadvantaged peoples of the world touches me.

At the end of a busy day, I take a moment to sit with all these thoughts.