One of the great issues in tax policy over the last few years was: how on earth did Dawn Primarolo keep her job as the minister responsible for HM Revenue & Customs?

She wasn't regarded as up to the intellectual complexity of the job, and those who worked with her have been less than flattering about her approach.

The latest book on Blair has at last solved the mystery. Well, we always suspected that Brown was protecting her, but now we know for sure.