Media: A Moment with Marquis.(the accession or inheritance of family owned businesses and crowns)

Margaret Thatcher once proclaimed famously that she would go 'on and on', although, to everyone's relief, she didn't. Tony Blair has generously announced he won't inflict on us a fourth term. But give him a tragedy or two and a microphone, and who's to say he won't be able to resist clinging to the top job until he is either ruthlessly toppled, Thatcher-style, or zapped by a hitman in the employ of Gordon Brown? And the Queen, 80 next year, shows no sign of handing over to Charles who, if his mother lives as long as hers did, won't be king until his mid-70s.

Rupert Murdoch is showing symptoms of the same affliction. The news that Lachlan, his eldest son and presumed heir, has quit News Corporation for a quiet life in Australia means James, the BSkyB boss, is now the only junior Murdoch contender.

Lachlan's decision has also prompted his father to reassert that his own retirement has been put on hold 'forever'. 'Indefinitely' may be a more accurate word but, then again, you never know with the Murdochs (Rupert's mother, Dame Elisabeth, is fighting fit at 96).

My guess is that, health permitting, Rupert will carry on until he is 80, five-and-a-bit years away. Even tireless control freaks are ultimately at the mercy of the years and it would be hard for anyone ...