"I am a busy man," I told them, "and an historian of intellectual bottom. What, pray, is the subject upon which you wish me to expound?" They informed me that the subject was the sex life of Queen Victoria: they would pay me the then princely sum of pounds 125."Quite out of the question," I riposted with all the contempt I could muster. "Arnold," they say, "we know you as a man of letters, a raconteur, a witty and waspish television panellist, an influential political theorist, an award-winning columnist, a Royal adviser and a man about town, but tell us this: which of these many hats were you wearing when first you rose to prominence?" And the answer to this brain-teaser is, of course, that I was originally a common-or-garden historian, a senior Professor of History at one of our oldest universities. I had already penned a number of well-considered historical biographies, among them learned tomes on Queen Victoria and Julius Caesar, when one day, quite out of the blue, I was approached by the old Daily Express with the request that I write 600 words. The proper response to the huge and growing power of London, the global city, is not to shrink into provincial bitterness but to start to plan for devolved assemblies in the English regions, and elected mayors in the big cities I love London, but this town needs a few pushy siblings.. WHEN, as so often happens, admirers approach me, I attempt to set them at their ease.

"Do ask me one question about myself - but only one! I am a busy man," I tell them, genially Needless to say, they then always ask me the same question. The devolution of power which is beginning in Scotland and Wales must spread to the English North, West and Midlands. Without the luck of having a great, hyperactive world city at one end of them, these islands would be greyer and less outward looking, less rich in possibilities. But this will not be a well-balanced nation so long as the power and influence continues to gurgle south without countervailing forces. A Britain without a self-confident Yorkshire, or a powerful North- east, will be a lesser place: the Victorians knew that.This takes us back to the politics Britain's reform agenda is still too timid. And that liberalism, now fully unleashed by the arrival of New Labour - itself a strongly metropolitan movement - curls into everything from social legislation to film censorship, from the choice of prize-winning novels to the characters and story-lines of TV comedies.In general, if London's leading Britain by the nose, that's not an absolute bad.

Closures or scandals in the City - the workplace of the spouses and friends of politicians and hacks - receive closer scrutiny than the same problems in other businesses.But the imbalance affects more than money and work For a lot of incomers, London is an escape from Britain Gays escape to London. London makes the whole country more liberal than it would otherwise be. When it comes to green issues, the green belt and commuting by car drown out equally important problems, such as agricultural pollution, or the degradation of the Midlands.But the general effect of metropolitan influence is liberating, not demeaning. So do tens of thousands of the rest of us: if you want to have a wild time away from your parents, or work in a cutting-edge job, or forget something about your social background, then London is the magic hatch that leads away from the rest of England, the great dissolver of the past.This can lead to tragedy - ''Your sons and your daughters are beyond your command/ Living in boxes just off the Strand'' - but it can also liberate and release the energies of people who would otherwise feel stuck and hemmed-in. At any rate, as a direct result of that youth migration over several decades, London political culture is more classless and fluid, and more liberal about almost everything, than the generality of British opinion.Not every effect of the London-Britain divide tends to the progressive.