It was not a very hard decision. I had been writing a reform of the welfare system for two years and wanted to see it through. My one-year contract with Labour was up in February and I had done the job I had been asked to do. But it is a difficult project to do in three years. In my time as an advisor I had three secretaries of state and five ministers of welfare. How can you run something which is so difficult and complicated with that kind of change?
Let that be a warning to David Cameron. The worst thing that can happen to a government department is to have a succession of different ministers within a short space of time. It means the department lacks direction and leadership. Obviously changes are sometimes inevitable, but David Cameron needs to learn from Freud's experience and resist the temptation to play musical chairs with his Ministers every year.