Alistair Darling came to the UK Treasury with a reputation for keeping disaster-prone departments out of the news. That record is now in tatters. Twice this week the chancellor of the exchequer has struggled to deal with crises on his watch. On Monday, it was Northern Rock. On Tuesday, he admitted HM Revenue & Customs had lost computer discs with personal and financial details of 25m people.

The resignation of Paul Gray, HMRC’s chairman, over this damaging error was proportionate. This is primarily a Revenue mistake and the right man has gone. But there are painful lessons for ministers.