By Nick Triggle Health reporter, BBC News

Ministers have been pushing GPs to work for longer

The British Medical Association has been a thorn in the side of many governments.

After the Second World War, doctors campaigned against the creation of the NHS with nearly nine in 10 voting to oppose the Health Service Act which paved the way for its creation in 1948.

In the mid 1970s, the trade union's negotiators were even said to have reduced the then health secretary Barbara Castle to tears in a dispute over pay.

And perhaps the clearest indication of the BMA's strength can garnered from Tory MP Ken Clarke who through his various cabinet roles has had to deal with police, teachers and NHS staff.

At the weekend, he described the BMA as the toughest trade union he had dealt with.

'Wallet'

And this from a man who was hardly cowed by doctors, once telling them during the Thatcher years: "Every time I mention the word reform, you reach for your wallet."

Too many that may have a certain ring to it as consultants and, in particular, GPs have done well financially out of their new contracts.

But despite facing almost constant criticism for this, the attacks in 2008 have been unprecedented.

First of all, health minister Ben Bradshaw - a former radio journalist who understands the power of a catchy phrase - took to the airwaves claiming the BMA did not "speak for the profession at large".

The BMA is still a very powerful organisation and politicians will still be very wary of its leadership Professor Chris Ham, former government adviser

And this came as his boss, Health Secretary Alan Johnson, was writing to GPs - bypassing the union in the process - urging them to accept the government's plans for extending hours.

The government received support from Dr Richard Horton, the editor of the Lancet, who accused the BMA of a "tissue of lies" over their scare stories about NHS reforms.

And this week, Richard Vize, editor of the Health Service Journal, a magazine read primarily by health managers, stuck the boot in, saying in an editorial that the BMA was treating GP care as "the personal fiefdom of its members".

Many believe the BMA's strength lies in the fact that they have managed to position themselves on the moral high ground.

Professional

Michael Sobanja, of the NHS Alliance, which represents health staff working outside hospitals, said: "The British Medical Association, in a similar way to the Royal College of Nursing, has presented itself as a professional body, when in actual fact they are registered trade unions that are there to look after their members."

But he believes that power-base is now at risk of unravelling as the union had been "weakened" in the battle over extended hours.

Our position is very much about guarding the future of the NHS Dr Richard Vautrey, of the British Medical Association

The BMA, unsurprisingly, rejects this. Dr Richard Vautrey, deputy chairman of the BMA's GPs committee, said members would continue to be vocal against reforms they oppose.

"Our position is very much about guarding the future of the NHS."

And despite the tribulations of recent weeks, there are plenty who do not see this as the end of the road.

Professor Chris Ham, a health policy expert at Birmingham University and former government adviser, said the public still trusted doctors above other professions.

"The extending hours dispute was really about the GP contract. Doctors were in a weak position to oppose it because of the big pay rises.