After celebrating his 70th birthday on Friday, Ratan Tata would in the normal course of affairs be facing mandatory retirement from the Tata Group. Two years ago, however, India’s most respected and acquisitive conglomerate ex­tended to 75 the age until which non-executive directors could serve, giving the man who has transformed it over the past 16 years a new lease at its helm. Although corporate governance purists at the time criticised the change as retrograde, it is a decision that few investors now regret.