They bear menaces rather than gifts - but new Labour is welcoming their ideas

Why can't Labour win general elections? One explanation is that Mrs Thatcher seized the intellectual initiative for the right back in the early Eighties, and the left has never managed to seize it back. Until it does so - until it discovers a Big Idea to rival the ones that worked so well for her - it is doomed to limp along behind the Tories, at best offering a new set of faces.

Think-tankers have nothing of the Establishment about them - neither classic genes, nor wealth, nor great address books, nor (necessarily) solid gold educations. What they have to offer is less in the way of gift-offerings than menaces: the "flying objects", as the late Richard Crossman put it, "that really terrify politicians: new ideas". Yet they are welcome at the feast: the bearers of new ideas are becoming prominent and are being feted in the Labour party as never before.

The left's intellectual fight back began with the setting up of the Institute for Public Policy Research (IPPR) back in 1988: a laborious name - in its logo the two "p"s are question marks - for what is disdained by its rivals as a doggedly Labourist outfit, too shackled to traditional Labour positions to come up with anything startlingly novel. IPPR basked under Kinnock's sun, but with his departure it found itself cast into the shade. Big Ideas remained elusive.

Perhaps there was more to be learned from those to whom Mrs Thatcher was not merely the devil incarnate. Two years ago some 95 intellectuals from all corners of the Left and none got together at Frederick's restaurant in Islington (Cherie Blair celebrated her 40th birthday there) to launch Demos, a think-tank which was to be genuinely open-minded: open to right ideas as well as left, and to experience from elsewhere (especially America). Demos got off to a splendid start when the Daily Mail derided it as "a ragtag band of one-time Communists, Hampstead socialists and quasi-experts", and it hasn't looked back.

Its director, Geoff Mulgan, who is 32 but looks much younger, is a plausible specimen of post-Thatcherite man: blond, slickly-suited, personable enough to have raised the pounds 100,000 needed to get the thing going. "He's the most brilliant person I've ever met," says a former associate, and he's nice with it. Like many of the brainy young, he's a graduate both of Balliol College, Oxford, and of Gordon Brown's office, where he worked from 1990 to 1992. He still has the great man's ear. Dennis Stevenson, chairman of the trustees at the Tate Gallery and a burgeoning New Establishment figure himself, is likewise a fan. And in its first years, Demos has built a formidable head of steam, tackling issues as particular as dentists and heating contractors, and as big as social democracy.

The problem is, it's so uninhibited. So when it turns its attention to social democracy, for example, its chosen sage, the former Thatcherite John Gray, declares (in his pamphlet After Social Democracy) "the central economic programme of social democracy is unworkable and social democracy itself a bankrupt project."

Hardly helpful. Demos is dynamite, but you can never be totally sure where or whom it is going to blow up. But if that dog won't hunt, there's always the Fabian Society to fall back on. In contrast to IPPR and others that have sprouted in the wilderness years, the Fabians go back to the glory days - to the Webbs and George Bernard Shaw. Even today, all but two members of Labour's front bench belong to it. The only problem is (people say) it's at its last gasp. But now a highly promising new general secretary has been appointed to administer first aid.

You don't need to be a reckless gambler to bet that Stephen Twigg (pictured) is a man to watch. Only 29, with the amiable, artless look of a large, startled hedgehog, he's another Balliol man, and went on to become president of the National Union of Students. Since then he has rarely put a foot wrong: he has been councillor then deputy leader of Islington council, and research assistant to Margaret Hodge, the Blairs' neighbour and confidant who is the new MP for Barking. At the general election Twigg will stand against Michael Portillo, and if he is unlikely to erase Portillo's 16,000 majority (he is openly gay, which may not help), he is at least likely to raise his profile a useful notch or two.

Twigg, like everybody else, is keen to discover that Big Idea, the philosopher's stone of new Labour which will turn its lead into gold. To that end he plans to revive the moribund Fabian Research Bureau, to take over the society's idea-generating function. But like a juggernaut bearing down, the election looms; there is little mental space at present for any Big Idea besides victory.