Cynical 10-year-olds have asked him how a fourth-century bishop from Asia Minor ended up at the North Pole and doubting Christians have asked whether he knew Santa was an anagram for Satan ("Neither time nor Christian doctrine lessens the appeal" is his reply). But he's never been asked this question before: "You've got black Santas and you've got women Santas," inquires an earnest, crew-cutted radio presenter. "But what," continues crew-cut, "about lesbian and gay Santas?" Richard, a PR man from Blackpool, who is acting as Santa's spin-doctor, looks worried.
Santa Tom is lost for words. "Er, well, I've, never had a problem with that," he mumbles. "You think it's a problem being lesbian and gay?" the questioner persists. A long pause follows. Finally, Santa Tom counters with: "Ho! Ho! Ho!"
Richard moves in quickly to steer his client, who is from Michigan, USA, towards the 30 fledgling Father Christmases who have enrolled.
"Ho! Ho! Ho!" roars Santa Tom. "I'm real pleased to be here." His wife, Mrs Santa (shouldn't that be Mrs Claus?) adds: "It's a real thrill, a real pleasure, to be in the wonderful city of London."
His students are asked to stand up and "ho! ho! ho!" in time-honoured fashion. Then they have to recite the reindeer names. After the novices sing a less-than-hale-and-hearty version of "Rudolph The Red-Nosed Reindeer", the students are ticked off for being too frosty. "You must be happy and positive at all times," Tom gushes. "Santa is a happy, jolly man. If you can be like this, you'll get your diplomas real soon."
Young mothers love Santa, Tom points out, but under no circumstances should you reciprocate their affection. "Please, no flirting. Some women want to come and sit on your lap. Don't take advantage."
Mrs Santa, still enthusing about being here, reads out a litany of flaws which leave kids cold, including wearing trainers rather than boots, giving too much "yo" and not enough "ho" and body odour.
"I'm not here to criticise," Santa Tom sighs. "But I must mention hygiene. You must take constant showers, constant breath mints." Mrs Santa nods.
At the end of the session on the North Pole, Santa Tom takes questions. "Are we allowed to make friends with polar bears?" one aspiring Santa wonders. "Ho! Ho! Ho!" Tom replies. "How many elves are there?" asks another. "886. You must know all the answers and always, always, keep in character."
"Remember, be positive," is the father of all Father Christmases' parting shot, as the day draws to an end. "Be a giving Santa. Give until you're exhausted. And then give again."
Meanwhile, Richard wants a photocall with some real reindeer, transported from the Scottish Highlands. Outside on Tower Bridge, unfestive film crews are hassling press photographers. "TV, will you MOVE, Santas, look this way. Get out of the way TV!"
Alan, from the Cairngorm Reindeer Centre is baffled. He has taken his herd to city centres and TV studios - "We did Esther on Friday" - but has never seen anything like it.
"Luckily, the reindeer roam free and unfettered across 6,000 acres," Alan says. "They can stand all this because they know they're going back to roam the hills." Ho! Ho! Ho!
Information on the School for Santas from Richard A Baguley at Cartmell Public Relations (01253 28928)