BBC News Online asked some of the doctors at the conference what their views were.

Dr John Wenham, a GP registrar from Bolton, Greater Manchester

"I'm not sure how much parents have an issue with the target payments system. I don't think they're overly worried about it.

"It's an issue for doctors, but I think parents are more bothered about whether there are adverse effects from the jab."

I find when I talk to parents, I deal with their anxieties by explaining what the evidence is

Dr John Wenham

But he said he did not think the answer was compulsory immunisation, a subject that will be discussed by the BMA on Wednesday.

"That's a difficult one. I think the aim instead has got to be informed consent.

"I find when I talk to parents, I deal with their anxieties by explaining what the evidence is."

Mr Fraser McLeod, a consultant obstetrician and gynaecologist at Frenchay Hospital, Bristol

"I think it is unfair on GPs to be penalised for public fears over MMR. They are very real fears.

"But I don't think the vaccination should be compulsory. There is such public concern, you have got to give people the choice."

Dr Akram Sayeed, a GP in Leicester

"Many patients think that we're recommending the vaccine for financial gain."

He added: "My practice has got a lot of refugees and asylum seekers on its list. Many of these patients are children.

Compulsory vaccination is something that ought to be considered

Dr Akram Sayeed

"It's a chaotic situation, because there are language problems and administration difficulties in getting them to have the vaccination.

"We have lost the higher target payment. We have been a victim of the system, which is beyond our control."

He added: "Compulsory vaccination is something that ought to be considered."

Dr Brian Patterson, chairman of the GPs committee in Northern Ireland

"I think it confuses the discussion between doctors and patients to have cash incentives."

He said although Northern Ireland had seen a slight fall in MMR uptake, it had not been as severe as the fall in England.

He added: "There should be a payment to GPs for work done, rather than for the numbers of vaccinations given.

"Patients should be able to trust that the advice given by their GP is unbiased."

Dr Simon Mintoff, an anaesthetist from Wigan

"You have to look at the evidence for and against. You have to follow all that, and give advice for patients.

"At the end of the day, patients do trust doctors. And if you give the information in a clear and balanced way, they will pick up the decision you make, and say, 'what would you recommend, I trust your decision'."