Where my parents grew up, there are few families which were not the recipients, willing or unwilling, of the genes of the Scotsmen and Welshmen who ran the Empire. My great-great-grandmother, born a slave, probably had never heard of Scotland when she met the sea-captain who fathered her umpteenth child. It is no accident that the men in my family carry names like Ivor, Angus and Mac, and so many black people have names like MacDonald, Phillips and Stewart. I am, by genetic inheritance and by culture, a romantic nationalist. And the abuse of that precious inheritance by mere politicians makes my blood boil.
The Old Nat politicians - and they are to be found in all parties other than the Tories - are muddled and outdated. They are no longer sure whether it is history, geography or ethnicity that drives their claim for self- government. As a result, they still cannot answer the so-called "West Lothian Question" - why should Scottish and Welsh MPs at Westminster have the right to vote on English matters once they have their own parliaments?
Nor have they explained why devolution would leave their people better off. Professor Douglas McWilliams, in his research for the City of London Corporation, reckons the flow of money out of London to be about pounds 6bn each year. Scotland and Wales are major beneficiaries. Government sources say that both countries take more from the Exchequer than they give back. Does anyone imagine that the London government promised by both Labour and the Lib Dems would simply keep writing the cheques with a cheery flourish? Not on your nelly. And if they don't, will the right to levy 3p in the pound make up the resulting deficit? No way, Jose.
There is a simple and compelling argument for administrative devolution. It is that government closer to the people is better, more effective government. But, the problem for the Old Nats is that the same set of arguments applies to virtually every other part of the UK. Physically, you can draw a line around the Black Country or Cumbria just as convincingly as around Wales or Scotland. Cardiff, as a centre of population, is nearer to London than Newcastle. Within Europe, Scotland looks much the same as the North-West of England, seen from Brussels.
But the Old Nats want to go to international conferences and pose as statesmen. So they fall back on the historic tradition. One wing of that tradition is institutional - the law and education particularly. We know that Scottish law is different. But that difference has been eroded over time, and the encroachment of EU competence will erode it faster. Eventually, the unique legal framework of Scotland will principally be a matter of archaic legal jargon. As far as education is concerned, it may only be a matter of time before England and Wales grasp that the Scots system is so superior that it is adopted wholesale across the UK.
The other wing of the historic tradition is what people now call "national identity". This constitutes the melange of cultural inheritance, speech, religion and just sheer tribalism, all traceable to an historic piece of land and water. The trouble for the Old Nats is that this justification for their ambitions is also on its way out.
To start with, Scotland and Wales are just as susceptible to globalisation as anywhere else. They have abandoned the kilt for Levis and their children turn up their noses at haggis when presented with a McDonald's. Second, they are divided: too many people in the northern half of Scotland dislike Edinburgh as heartily as they do London, and distrust it more. The same is true of north Wales and Cardiff. Third, Scottishness and Welshness are increasingly spread outside the traditional borders; if Labour wins, its three most dominant figures - Blair, Brown, Cook - will all be Scots. And, fourth, the Old Nats' conception of devolution offers no promise to those outside the borders of Scotland and Wales who feel themselves to be part of those nations. Do we get postal votes in the elections, or is this a property-based franchise, in which second-home owners have rights not available to people who can trace their ancestry back two centuries?
To make matters worse for Old Nats caught up in the romantic tradition, there are stronger claimants to an undiluted historic tradition in modern Britain. Two million dedicated British Muslims are entitled to ask why it is that they can expect, at best, one Muslim in the new Parliament, while a similar number of people who happen to live in Wales - but many of whom can't claim a Welsh heritage - can demand 30 members of Parliament, a government of their own and a pounds 3bn subsidy.
If the response is that the coincidence of population and geography is the key, the Old Nats are missing what is going on in the world. I know from my own experience that nationhood transcends geography - a lesson that Irish and Jewish nationalists have exploited brilliantly for most of this century; arguably, their greatest achievements have not been the establishment of Jewish or Irish states, but the creation of rich, vibrant and modern global tribes. Take also, for example, the success of East African Asians - built on the existence of a 150 million-strong diaspora that stretches across three continents, sharing common tastes, buying the same goods, watching the same films. In my own global tribe, it is no surprise to me that the top TV show among black South Africans (New York Undercover) is the same as that among African-Americans and probably among black Britons who can see it on satellite, yet the show is unknown to white audiences.
If the Tories lose, there will be devolution. But after the first flourish of ceremony, the real symbols of Scottishness and Welshness are as likely to be found on cable or satellite TV as they are in the talk shops of Cardiff or Edinburgh, doomed to be starved of cash by Whitehall, and destined to be overruled by Westminster and Brussels. The truth is that the modern nationalist doesn't need another stuffy debating chamber. A modem, a PC and a satellite dish will do nicely, thank you.