By Jeremy Clay

There are plenty of things you might reasonably expect to feature in a show called Monster Moves (8pm, Five).

Trucks, for instance. And tracks. And squally showers of welding sparks, accompanied by all manner of hammering, drilling and generalised thumping, thudding and power tool vvvwwwwaaareeee-ing.

Plus, enough builder’s bum on display to meet the morning rush hour demand for bike stand space in downtown Beijing.

Yup, that’s the kind of thing you’d bank on: Gruff men with beards and/or tattoos shifting large stuff.

And that’s pretty much what we got, along with something rather less foreseeable: a narration by a choir.

For the first 15 minutes of the show, there’d been nothing to suggest anyone was going to burst into song. Still less the kind of choral narrative that ancient Greeks used to chivvy the story along in a tragedy.

Until then this had been a routine bloke-doc; the kind of thing that appeals to people who like rivets but find Scrapheap Challenge a little on the frivolous side.

There was a decommissioned submarine in one bit of Canada. And it was going to be towed off to another bit of Canada, where it would wind up the ta-da! centrepiece of the nation’s first sub museum.

So a little tug chugged out of Halifax with the submarine bobbing along behind. It was strangely comforting to watch.

Then – without warning nor explanation – the massed voices of the Crouch End Festival Chorus waded in to the plot.

“The final voyage of a war machine,” they sang, as the sub headed north. “Canada’s submarine, hatches sealed, maps are read, heave-ho full steam ahead.”

What the ....?

“Heave-ho, under tow, we’ve got a way to go, heave-ho, journey’s slow, pulling her home.”

But here’s a thing. After a moment or two of sheer incredulity, in which it seemed the director must have been sniffing Amy Winehouse’s armpits, it suddenly became clear that this was Quite A Nifty Idea.

Sure, it was shudderingly odd, but it worked. Somehow.

In fact, I’d go as far as to say there should be more choir-based narration in documentaries.

Hell, let’s have it on the news too. If we’re going to be plunged into a nightly depression by a series of spirit-sapping credit-crunchy-climate-changey-terror-death headlines, we may as well have a jolly old sing-song.

ITV are trying to find The World’s Best Diet (8pm) by sending the likes of Carole Malone, Cheryl Baker and Linda Robson off to places like LA, India and Japan to eat like the locals.

What have we learned so far? Not to tune in again, chiefly.

Oh, and that Cheryl Baker is plagued by flatulence. Maybe that’s what sparked Bucks Fizz’s celebrated skirt-swiping routine.

They needed to do something to waft away the whiff.