Chuka Umunna recently bumped into the veteran Liverpool MP Peter Kilfoyle at the Palace of Westminster. Umunna explained that he hoped to enter the Commons at the next election as the Labour MP for Streatham in south London. Kilfoyle asked what he did for a living. When Umunna said that he was in the law, there was a sharp intake of breath from Kilfoyle. "Not another bloody lawyer," he said, before wishing him luck in the appropriate comradely fashion.

At 30, Umunna has already been talked of as a future Labour leader and as "Britain's Obama". Yet, despite his "modernising" credentials, he is fast developing a following on the left of the party. Closely associated with the centre-left Compass group, he is dismissive of the new Labour old guard that has dominated party ideology since the mid-1990s. Last year, he even went so far as to argue that new Labour "at its crudest . . . was predicated on a cynicism and a pessimism about the British public". Criticising the tactic of triangulation, Umunna called for Labour to stand up for its core beliefs by making "emotional arguments" for fairness and redistribution, just as Margaret Thatcher had done for the previously unfashionable thinking associated with Hayek and Friedman.

He has advocated windfall taxes on energy companies and supported Jon Cruddas's call for a 45 per cent top rate of income tax for those earning over £175,000 a year. Challenged recently by a new Labour architect about his associations with Compass and its dangerous ideas, which would take the party back to the wilderness years, Umunna responded by saying that he was still a toddler in the 1980s, and that, as far as he is concerned, it is now new Labour that is dangerously old-fashioned.

"There is a new generation of politicians who weren't part of the depressing years in the 1980s and 1990s," says Neal Lawson of Compass. "As a result, they're much more hopeful. People who are very ambitious want to be a part of the mainstream. Chuka is different because he is ambitious, but he wants to shift the mainstream to a more radical form of politics."

His mix of aspirational values and passion for social justice reflects his background. His Nigerian father, Ben, came to Britain in the 1960s, cleaning cars and then setting up a successful import-export business. His part-English, part-Irish mother was a probation officer. After Manchester University, Chuka became a solicitor, initially at the City firm Herbert Smith, specialising in employment law. As well as being a trustee of two youth charities, he is the editor of TMP, an online magazine for "multicultural progressives".

Umunna made his mark with a combative appearance on BBC1's Question Time in October 2007, taking on the former Sun editor Kelvin MacKenzie. "Showing how he could handle a situation like that was crucial," says Lawson. "He came of age that night."

He has another quality that will serve him well in future. As one seasoned campaigner puts it: "There is one way he is different from the people running the party at the moment - he always remembers your name."