Thousands of doctors have marched in protest at reforms to medical training, accusing the Government of trying to "disempower and degrade" the profession.
Vocal protests were staged in London and Glasgow, despite last-minute promises from ministers that junior doctors would be given a second chance to progress their careers.
Tory leader David Cameron delayed travelling to his party's spring conference in Nottingham so he could attend the event in the capital, and told the crowd the changes to training were a "shambles".
He said the Conservatives would treat doctors like "human beings", and pledged to hold the Government to account over the Modernising Medical Careers scheme - which has come in for widespread criticism from the British Medical Association, Royal Colleges, senior medics and trainees.
"The Government have said they are having a review (of MMC)," Mr Cameron said.
"It's got to be a proper review not a paper exercise, and if they can't get it right they've got to scrap it."
The scheme was introduced by the Department of Health in a bid to find a fairer way of placing junior doctors in over-subscribed training roles.
At least 30,000 junior doctors have applied for up to 22,000 specialist posts under MMC, which it was hoped would speed up the training process of becoming a consultant.
Reported problems include computers crashing, non-medically qualified people being involved in the short-listing process, and scant information on qualifications being available to interviewers.
on Friday night the Government announced that 5,000 more doctors will now be interviewed and considered for selection for the sought-after roles.
