By strange coincidence, the previously little-known MP for Poplar and Canning Town, Jim Fitzpatrick, has been thrust into the limelight as a key aide to both the current health secretary, Alan Milburn, and former health secretary Frank Dobson.

In the Commons he is Mr Milburn's parliamentary private secretary: unpaid bag carrier and factotum, and his boss's 'eyes and ears' on the backbenches.

Outside Westminster, he is chair of the Greater London Labour Party: as such he has clashed with Ken Livingstone and become a key figure in Mr Dobson's stuttering campaign to win Labour's London mayoral nomination.

Like Mr Milburn, his New Labour loyalism hides a history of left-wing activism. He even left Labour to join the Socialist Workers Party for a time in the late 1970s.

But the ex-fire fighter and Fire Brigades Union official's experience of Trotskyist organisational discipline has undoubtedly held him in good stead. He is known to both admirers and critics as Jim 'Fixpatrick'.

A leaked report on a Labour Greater London Executive meeting, quoted by a Conservative MP during debate on the Greater London Authority Bill in 1997, noted how 'chair Jim Fitzpatrick manipulated the meeting shamelessly'.

He has rebelled against the government - on plans to abolish student maintenance grants in May 1998.

His subsequent appointment as Mr Milburn's PPS at the Treasury should not have been entirely surprising: after all, as health minister, Mr Milburn's first PPS was spiky left wing MP for Halifax and ex-health committee veteran Alice Mahon.

But critics felt vindicated. Left-wing magazine Red Pepper had written of Mr Fitzpatrick: 'He is an accomplished compromiser who keeps his options open - feared to lack the strength of personality to retain political independence and may fall at the first offer of patronage.'

His parliamentary record - he was elected in 1997 - shows little sign of an active interest in health issues, aside from Sport for All and support for antidrugs campaigns.

His political career looks bright, particularly with Mr Milburn's star in the ascendant.

If Mr Dobson gets the Labour nomination, and becomes mayor, Mr Fitzpatrick's future looks even brighter.

And to cap it all, his dog Scruffy has been a consistently high achiever in the Westminster Dog of the Year contest.