The exam would be at the end of medical school, before the MRCP or MRCGP.
Chris McManus, professor of psychology and medical education at University College, London, found that medical schools leave their stamp on a student's postgraduate performance, irrespective of academic ability.
MRCP candidates from Liverpool and Dundee were most likely to fail, while those from Oxbridge and Newcastle were most likely to succeed.
A new MRCGP league table ranks medical schools in very similar order to the MRCP one.
Professor McManus lays the blame on ‘medical-school related factors'.
‘Graduates from different medical schools perform markedly differently in terms of their knowledge, clinical and communication skills,' he said.
‘There seems to be a strong case for a national exam,' he added.
Liverpool shares bottom place in the MRCGP league table of 23 medical schools with Manchester and King's College, London. Dundee comes eighteenth but Newcastle and Oxford are second and third.
The league table , prepared for the RCGP's examination board, shows that pass rates among 3,787 graduates in 2003/6 echo medical schools' achievements as long ago as 1988 to 1991, when Oxford topped the table and Liverpool and Dundee took two of the bottom four places.
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