In the past five months, Lord Myners has been at the forefront of Gordon Brown's efforts to prevent a financial meltdown.

As a former chairman of the Guardian Media Group and a Labour party donor, Lord Myners is viewed by the Government hierarchy as that rare thing: a senior figure from the Square Mile who has a social conscience. Or as he has put it: "I have worked in the City but never been of the City."

Last month, he dispensed with the niceties of political language to rail against his former colleagues, attacking some as "grossly over-rewarded" people who "have no sense of the broader society around them". The Treasury quickly distanced itself.

Paul Myners has the most humble of backgrounds, spending his first three years in a Cornish children's home before being adopted.

After winning a scholarship to Truro school and a place at London University, he embarked on a teaching career but abandoned it for financial journalism before switching to banking.

His stunning success in boosting the profits of the hedge funds of the Gartmore pension company was the start of his rise to the upper echelons of corporate Britain.

He combined directorships with big names like British & Commonwealth, NatWest, O2 and Orange with work for organisations such as the Tate Gallery and the Low Pay Commission.

As the head of Marks & Spencer, he saw off an attempt by Sir Philip Green to take over the retail giant.

Immediately before his appointment as City minister, Lord Myners was chairman of the Guardian Media Group and Europe's largest property developer, Land Securities Group. By this time, his Labour sympathies were well known. He gave £12,700 to Mr Brown's leadership campaign in 2007.

His ennoblement with responsibility for the City and his appointment to Mr Brown's new National Economic Council has left him working punishing hours.

But colleagues say the new multimillionaire peer, who works out of a chauffeur-driven car, remains focused and ruthlessly efficient, although he worked through the night in October on the detail of the first bank bailout. Others are disconcerted by his habit of seizing on the weak spot in a colleague's argument.

Today it is Lord Myners who finds himself in an unforgiving spotlight.