Last summer, after nearly a decade of training, Dr Jayne Graham qualified as a GP. She's spent the last three years at an NHS practice in a deprived part of South London, and had planned to stay there. Today, however, she's working for a private clinic in affluent Kent.

Dr Graham - not her real name - hasn't joined the dark side because of some damascene conversion to the superiority of private medicine. Instead, like hundreds of her colleagues, she simply found that the NHS didn’t have enough jobs to go round.

"This isn't at all why I wanted to be a GP, but I’ve got to pay my mortgage," she says. "I believe patients should be treated based on need. But I’m giving out private treatment because I have no other option."

She's not alone. Nationwide, the number of advertised vacancies for GPs has dropped by as much as 70 per cent in the last year. The BMA estimates that 1,000 of this year's crop of graduates – around a third - will struggle to find work.

As a result, young doctors are grabbing any work that's going. Some are working part-time; others as locums, doing the medical equivalent of temping. At least one is driving a London taxi. Others still, with £60k of debt and a quarter of a million pounds worth of training behind them, are doing precisely nothing.

The most worrying contingent, though, are those like Dr Graham who have left the NHS altogether. Several of her colleagues have already made the move ("Where else are they going to go?" she asks, pointedly).

Plenty more are considering it. In 2006, a survey by medical newspaper GP found that less than a third of young doctors would work in the private sector. Last July, when it repeated the exercise, that number was more than half. One of the younger BMA reps says that many of her colleagues are setting up private pensions, "because they don't think the NHS is even going to be their main employer any more."

Comments like this may surprise those who still tremble with rage over six figure pay packets for doctors.

In fact, those are a big part of the problem. The contract that created them works on the basis that the partners in each GP practice split its profits. This, it turns out, is a big incentive not to bring in any more partners. The GPs, of course, place the blame squarely on the government’s refusal to increase funding for the last three years, in an attempt to claw back the embarrassingly huge pay rise of 2004.

But while the BMA and the government have been busy blaming each other, the private sector’s been cashing in. For the last few years the medical profession have been the main opposition to NHS privatisation, leaving business to grumble about medical protectionism. Now, though, companies are scheming to bring doctors on board with cushy pay and conditions. US giant UnitedHealth Europe is offering terms so generous they get praised to the heavens at conferences. Virgin Healthcare is going one better, allowing GPs to keep their NHS status, but co-opting them to the Branson brand so that it can flog private health and dental services to those with spare cash and no patience.

The doomsday scenario here is that general practice could go the way of dentistry, where it’s now all but impossible to get NHS treatment in some parts of the country. Dr Alex Smallwood, who represents GP trainees at the BMA, warns that, if the situation isn’t resolved soon, we’ll "hit a bubble down the line when GPs have all gone private, and there aren't enough to staff the NHS."

That’s unlikely. What’s more probable is that one of the last barriers to the commercialisation of the NHS will start to break down. The more GPs who take private jobs, and discover they aren’t so bad, the more likely the profession will be to rethink its stance on private healthcare.

It's unclear how to solve this mess. The BMA, which has spent much of the last year denying there's a problem, now says it's working on proposals to encourage practices to create jobs. But while its head GP, Dr Laurence Buckman, admits it’s "a very dangerous situation," he adds, "We can't take any concrete steps because GPs are independent contractors". Meanwhile the government gets what it wanted all along: a more competitive NHS, and a way of putting downward pressure on GP salaries.

Whatever happens, things will likely get worse before they get better: the number of GPs being trained up is increasing by 400 next year. Dr Graham won’t be the last doctor who goes private.