Watch out for flying fish

IF you’ve recently flown from Heathrow to LA, did it occur to you how many fish you were sharing the flight with? It didn’t? Golly, well, in that case you’re in for quite a surprise if you watch WHAT BRITAIN BUYS AND SELLS IN A DAY (BBC2, 9pm). The answer, assuming yours was a typical flight, is lots.

Beneath your seat, unbeknown to you, there may well have been up to 30 tonnes of salmon.

Not directly beneath it, I should stress (imagine the mirth if you had needed to reach for your inflatable lifejacket and found nothing but a slippery fish) but down in the hold, in the bit where your suitcase goes.

Yes, that’s right, alongside your luggage – regarding which, ironically, you’ll have been warned of the penalty if you dare let that extra pair of socks push it over its weight limit – there’s likely to have been as many as a dozen huge pallets, piled high with boxes of this top-end Scottish produce, headed overseas.

This is the case, we’re told, on roughly 90 per cent of long-haul passenger flights.

If it’s not Scottish salmon (which it so frequently is because we export so much of the stuff) it’ll apparently be something else splendidly British that’s in equally high demand – such as, presumably, Marmite or irony.

Yes, it’s big business for airlines, renting out vast areas of passenger aircraft hold space that would otherwise stay empty.

Learning how it works – and, in this case, about the all-important salmon price index – is one of this show’s hosts, top ballroom dancer Ed Balls, who gets a lesson in the economics of the process from a Heathrow-based logistics guy.

Ed does sound as if he’s struggling to grasp the arithmetic at one point.

But eventually the penny drops. “Oh, I see!” he cries. “If the price goes DOWN, more people want to buy it?”

Yes, that’s right, Ed.

Phew, thank goodness this chap was never shadow chancellor.

Elsewhere, MOTORWAY BRITAIN: 60 YEARS OF SPEED (Channel 5, 9pm) recalls how a road revolution began with high hopes. Before it gets to the all-too-familiar modern footage of tailbacks and prangs, there’s a nice crackly clip from 1958, of Prime Minister Harold Macmillan opening the first of such radical new roads.

“I now therefore will press the appropriate button,” he declared, “and, all being well…I shall formally declare the Preston by-pass to be open…”

Of course, his proviso there

– “all being well…” – followed by a mischievous pause even Boris would be proud of, suggests Macmillan had rather more foresight than history gives him credit for.