activist.

But those who know him beg to differ. Mr Hill, they say, is “gung-ho” for privatisation, an ultra-moderniser, unlikely to take a conciliatory approach with unions.

He takes over from Chris Boffey who left when Estelle Morris, Mr Clarke’s predecessor, resigned.

Mr Hill has about as low a profile as is possible for someone with his position and contacts. It is almost impossible to find out about his background. The Department for Education and Skills was unable to provide a CV, while Downing Street said it did not give such details on special advisers as they are “private individuals”.

What is known is that as well as being a former theology student and binman, as a NUPE official he was active in the 1982 NHS strike. He went on to work for the Audit Commission and, ominously to some, Capita, the firm that runs many contracted-out services.

Since then he has become a powerful figure in Blair’s “kitchen cabinet” first as a health specialist and then as the Prime Minister’s political secretary. High-profile ideas such as NHS Direct are said to be his and he is thought to favour giving some hospitals power to borrow money from the private sector.

“In our experience he is quite gung-ho about privatisation,” said one official at a teachers’ union. “I was disappointed when I heard Charles Clarke was taking him.”

Some commentators say that he is a conciliator, who can defuse the sort of rows between the DfES and Number 10 that were seen when Estelle Morris and adviser Andrew Adonis failed to get on. But those who have dealt with him feel this is unlikely. “He doesn’t strike me as a conciliator or mediator,” said one.

Undoubtedly, however, the arrival of one of Mr Blair’s key advisers will reinforce the widely-held view that Mr Clarke is the Prime Minister’s man. The verdict of the unions? Treat with caution.