A senior health official criticised by the Tories as a Labour sympathiser has been put in charge of the body tasked with taking the "politics" out of NHS board appointments.

Sir William Wells has been appointed chairman of the new NHS appointments commission, which will choose chairmen and non-executives to sit on the boards of trusts and health authorities.

The commission was set up as a means of removing the constant political wrangling over the 3,000 board positions, which have in the past been seen as partisan "grace-and-favour" nominations in the gift of the health secretary.

Sir William, who is the non-executive chairman of the NHS south-east region, was earlier this month accused by Tory health spokesman Liam Fox of applying "enormous and unnaceptable political pressure" to NHS trusts.

Sir William had sent a letter to trust chairmen in the south-east region in which he said he "cannot over-emphasize the importance of achieving our manifesto commitment" of reducing waiting lists.

Dr Fox last night said Sir William's new role was "simply unacceptable" and "made a mockery of any notion of impartiality in the NHS".

He added: "It shows that willingness to comply with ministerial diktat is now best way to get on in the NHS."

Sir William told SocietyGuardian.co.uk: "I have never been a member of any political party in my entire life. I have been involved as a non-executive in the NHS under governments of all different colours."

He described Dr Fox's comments as "bizarre" and pointed out that the shadow health secretary had "never bothered to talk to me" about his political sympathies.

"What Dr Fox forgets is that it was his party that appointed me as a regional chairman in the first place."

Ironically, many in the health service believed Sir Wiliam to have been a Conservative sympathiser because of his track record as an enthusaistic proponent of the Tories' internal market NHS reforms in the early 1990s.

Sir William attracted further controversy last week when it was alleged that he had "delivered" the resignation of a trust chair in the region to Alan Milburn before she had even made the decision to part company with the NHS.

According to Health Service Journal, Sir Wiliam told Gillian Miscampbell, the chairwoman of Stoke Mandeville Hospital trust - and a Conservative councillor - to "resign or be sacked" over a waiting list scandal.

Sir William has served as a non-executive board member in various NHS organisations continuously since 1968.

He was appointed by then health secretary Kenneth Clarke as one of the 57 elite "first wave" of NHS trust chairmen in 1990 with the aim of taking forward the reforms.

He was a founder member of the NHS Trust Federation, a body set up to champion the reforms, and was knighted in 1997 by former prime minister John Major.

There was widespread surprise when he was not only retained as an NHS chairman by Labour, but became a trusted senior figure who became as enthusiastic a proponent of Labour "modernisation" as he was earlier of the Tory internal market.

Roy Lilley, a former first wave trust chair and colleague of Sir William, said he had "always found William's politics difficult to read", and that he was often privately cynical about politicians.

But he added that Sir William must have been seen as acceptable to the then Tory government to become a first wave trust chair: "Everyone had some connection through the (Tory) central office network."