sentences:  He has since returned to HM Treasury as a managing director and is the government's representative on the board of Northern Rock following its nationalization.On 1 April 2008, Sir Michael became the 3 day-a-week non-executive chairman of the new UK Statistics Authority (UKSA), through which the National Statistician is accountable to Parliament.The board oversees the Office for National Statistics, following the "independence" which it obtained from ministers in the Statistics and Registration Service Act 2007.