Chimneys! Once upon a Really Very Recently, the roofs of the world bristled with them, as if every city was nothing more than an overgrown, hedgehog made of bricks. And for Santa, each chimney was really a door from the sky.

But things changed. First chimneys became, ahem narrower (or at least that’s what Santa claims, and he gets quite agitated if an alternative explanation is suggested). And then, slowly, they began to disappear.

Not that Santa misses the soot, as it takes him several days to get his beard clean – and his suit’s always a mess too. However, the loss of chimneys meant Santa had to find other ways to access homes and leave behind his gifts.

As it happens though, Santa is, among other things, an accomplished burglar. Which shouldn’t be too surprising, since he famously jogs along starlit roofs with a swag bag slung over one shoulder.

Thing is, there’s a problem, as Flora Kunningbear put it in her book “The Frights Before Christmas: A History of all the times it nearly Went Wrong”: which is that lockpicking takes an awful lot longer than chimney-swooshing does.

“Lockpicking takes an awful lot longer than chimney-swooshing does.

Flora Kunningbear, from ‘The Frights Before Christmas: A History of all the Times it nearly went Wrong’

And then there’s the look of the thing. Roll forward to when a New York police officer got the wrong idea upon seeing a shadowy figure hunched by a doorway, fiddling with the lock. A blushing Santa very nearly spent Christmas Eve in the drunk-tank that time…

It’s pure guesswork to imagine what might have happened if Blitzen hadn’t wandered down to see what the delay was. But, as you’d expect, 170 kilos of furious reindeer soon helped persuade the police officer of Santa’s true identity. And that it would be a very, very bad idea to be chucked onto next year’s naughty-list, if he didn’t want to find ALL his socks filled with sloppy reindeer poo!

Altogether, it meant that Santa had to find an improved way to get into houses.

Thankfully, Santa’s Research, Engineering, Design Helpers and Tech Tinkerers (REDHATTs) managed to come up with ‘ghosting boots’. These briefly turn normal matter into ghost-molecules upon contact, and now Santa simply plunges through ceilings as easily as kingfisher dives into water.

Although, it must be admitted, he does so with a lot less elegance, and often lands flat on his bottom!