Roman Abramovich may have spent more than half a billion pounds on players for his beloved Chelsea, but the abrupt departure of yet another manager suggests it is patience he needs as much as talent on the pitch.

André Villas-Boas was the seventh Chelsea manager, no less, since the Russian oligarch took over in 2003. A swift glance around the Premier League, however, suggests a link between longevity and silverware that Mr Abramovich is overlooking. The most obvious example, of course, is Sir Alex Ferguson, who has been at Manchester United for 26 years.

Indeed, length of service is not the only lesson to be drawn from Sir Alex. Three years into what would become the most successful managerial career ever, Man U had a rocky patch that left them only just safe from relegation. Had the club's chairman been too hasty, Fergie's vast talents might have been lost.