it was safe to assume, as with Cheney's, that potentially troublesome legal residents would have been locked up, then kicked out.

These are negative reasons, of the sort that guided me in earlier years to elect to be Irish when I got my first passport. I had the choice between the UK and Eire as it was then called. I was pondering this when our school radios announced in 1956 that the RAF had bombed Ismailia as a first blow in the Suez invasion.

The lads in our Patchell's house room in Glenalmond rose to their feet cheering. My sympathies were with the Egyptians. I remained seated and listened to a heated debate as to whether I should be tried and hanged as a traitor. It seemed better to be Irish.

My brothers Andrew and Patrick made the same decision about citizenship a few years later. Patrick was vindicated in 2005 when Shia fighters at a roadblock in southern Iraq asked to look at his papers and when they saw his passport was Irish let him pass. Patrick reckons that if he had been carrying a UK passport they would have shot him on the spot.

After three and a half decades, why be a non-voting (albeit tax-paying) visitor, particularly if you've been dispensing measured counsel for many years on how the place should be run? I've lived in every quadrant of the United States and driven across it maybe 40 times – not hard when you live in the west and buy old cars from a friend in the south east. I know the place as well if not better than many. And though on conventional reckoning it might seem late to start that long journey to the White House, the lure is strong.

Now it's true that Article 2 of the US Constitution states that "No Person except a natural born Citizen, or a Citizen of the United States, at the time of the Adoption of this Constitution, shall be eligible to the Office of President". But if we are to believe a flourishing conspiracy movement, Obama has successfully nullified that provision.

A substantial number of Americans argue strongly that his father's Kenyan citizenship, not to mention the refusal of the state of Hawaii to release his original birth certificate, throw Obama's eligibility into question.

My mother claimed I was born a Sunday and delivered by a doctor in a kilt

Simiilar mysteries attended my birth. I was born on June 6 - so my handwritten birth certificate states - in a large house owned by an American woman, in Bonar Bridge, near Inverness. It was wartime and my father, a noted Commie, wasn't allowed into that bit of Scotland.

For years my mother claimed I was born on a Sunday and delivered by a doctor in a kilt summoned from a nearby river bank where he was fishing. I looked up June 6, 1941 on my computer recently and it was a Friday, not a Sunday. Three missing days - a gap big enough to drive a presidential bid through.

But who'd want to be president, you ask. Look at Obama. He talked of change, of hope, of persuading America to sink its differences and move on. Five months later he's hitting roadblocks manned by forces rougher by far than the Shia lads who spared Patrick: the insurance industry, the drug companies and the American Medical Association - all of them implacably opposed to his hopes of edging towards some sort of universal health coverage; the Israel lobby and prime minister Netanyahu, all furious at the idea of curbing Israeli settlements and giving Palestinians a state in fragments of their former land; the arms companies and their sales reps in Congress, who have had free rein for 60 years.

It'll be eight more impasse-ridden years, and then... It will be time for the man on the white horse, or in my case Agnes, a chestnut mare, half-Arab, half thoroughbred, getting along in years, but a worthy successor to the steed bearing my ancestor, Admiral Sir George Cockburn, who entered Washington and torched the White House in 1814. He sent soldiers to the print foundry of the local paper and instructed them to destroy all the Cs , "so that the rascals cannot spell my name."

Cheney would have approved. Running against Washington is always the default option for an American politician. Here I come.