When it comes to motorhomes, I’m a real sucker for a TARDIS. For those who aren’t of a Whovian persuasion, TARDIS is an acronym for ‘Time And Relative Dimension In Space’. It’s Dr Who’s transport of choice. It looks like an old police telephone box. And it sounds like it’s in constant need of oxygen.

But its big party trick (and I promise that there is a motorhome-related point somewhere in this blog’s immediate future) is managing to squeeze a colossal interior into a tiny little box. And let’s be honest: isn’t that the motorcaravanner’s ultimate dream?

All fantasy nonsense, of course. Or is it? I’m not so sure. If there’s one thing I’ve learned over many years of testing motorhomes, it’s that you should never judge a book by its cover. Colossal American RVs, for instance, might look very impressive with their slide out this and V10 that, but some of them can only sleep four people. The similarly four-berth Romahome R40, on the other hand, fits easily into a standard car park space. I know this, because I’ve done it.

The TARDISes I’ve encountered recently fall somewhere in between these two extremes. Each can accommodate six full-size people within a conversion that you wouldn’t baulk at threading along a Cornish lane. And each is British through and through.

First is the Swift Escape 696. You might remember it from our December 2014 issue cover. It swallows six with consummate ease. But take another look at it. It might be nearly 7m long, but it’s not exactly a bus, is it?

I put a lot of mileage on that motorhome, on all sorts of roads. And if there’s one immutable truism when it comes to working with a professional photographer (as I was on that day), it’s that you will be expected to perform a variety of three-point turns in the pursuit of The Perfect Shot, irrespective of how little room you have in which to manoeuvre. That photoshoot was no different, and at no point did I feel like I was grappling with an elephant in a telephone box.

And yet, step aboard, and it’s a vision of space. There’s room for at least six people in the forward lounge, and looking aft from the cab suggests that it’s going to be quite a stroll to the commodious fixed bunks stacked along the rear wall. Better yet, everyone can still get to the loo, even with a full complement of people snoring on board. It really is a proper feat of physics-bending engineering.

More recently, I had cause to spend quite a bit of time in another six-berther. At 7.4m stem to stern, the Marquis Majestic 180 is quite a bit longer than the Swift (good luck with getting one of these into your average NCP), but once again, it seemed to shrink around me the longer I spent with it.

Part of the reason for this, of course, is the grunty 150bhp engine (standard Autoquests make do with 130bhp). But such is the sheer staggering driveability of the latest Peugeot Boxer, that within 10 minutes of scooting up the M3, I’d pretty much forgotten that there was the equivalent of a two-bedroom flat behind me.

And while this is no shrimp, it’s no tag-axle A-class monster either. Find a car park with no height restrictions, generous-sized bays and plenty of surrounding space (over which to reverse the colossal rear overhang), and you might even be able to park – just – alongside Mr and Mrs Smug in their Romahome R40.

Best of all, Swift and Elddis are far from the only manufacturers who routinely pull this magic trick off year after year. So if you think big space in a manageable-sized motorhome is the unattainable dream – don’t despair. There are plenty of engineers out there right now who probably have a sonic screwdriver somewhere about their person.