It is Jubilee week: bring out the national treasures! And so here are Gary Barlow and Andrew Lloyd Webber, tasked with writing a song for the Queen.
"Our mission is to capture the sound of the Queen's greatest achievement: the Commonwealth," says Barlow, at the start of On Her Majesty's Service, a one-off BBC One documentary. (It seems not entirely in the spirit of the occasion to point out that the Commonwealth - or "Empire", as it was known then - was actually the achievement of a different queen.) So Barlow sets off on an international music odyssey. Or, as the rest of us might call it, a holiday.
His first stop is the Kenyan safari lodge where Elizabeth went to bed a princess and woke up a queen. Here, a girl called Lydia records the opening lines of the song. Barlow enthuses about "the little bit of pronunciation that tells you: she's not British, she's not American. She's from somewhere else." Ah, the Commonwealth: somewhere else.
But listening to Lydia sing is actually quite moving. So is watching the Slum Drummers, a group playing relentlessly upbeat music on instruments made of scrap metal and plastic.
Next, Barlow heads off to Jamaica. He climbs a mountain and meets a Rastafarian priest. "There's a nice smell in the air here," he says. Prince Harry is also in Jamaica, as part of his Diamond Jubilee tour. Or, as the rest of us might call it, a holiday. He taps a tambourine and Barlow adds it to his growing collection of musical samples.
Barlow is constantly "amazed" and "uplifted". But there is an honesty to his amazement: this is not purely for the cameras. And the process of putting together an internationally sourced song is pretty amazing. Despite myself, I feel quite moved.
The final stop is in the Solomon Islands, where a marching band plays a brassed-up version of The Final Countdown.
Back in London, the main vocals are provided by a military wives' choir. "Absolutely red, white and blue the whole way through," the choirmaster says of his singers.
I am no royalist. Still. Maybe it is good editing. Maybe it is the irresistible likeability of Barlow. Maybe it is the emotional intensity of Prince Harry's tambourine taps. But when the opening verse begins to play, dammit, I feel proud to be British.
Gary Barlow: On Her Majesty's Service, BBC One, 7.30pm, Sunday 3 June.