With the “improve, don’t move” mantra ringing in their ears – sometimes fuelled by a reluctance to pay the huge stamp duty bill involved in upsizing to a bigger house – many homeowners are finding a new way to extend. They’re buying next door.

In certain situations, it can make perfect sense. You love your house and the location, but you need more space, perhaps because of boomerang children or grandparents moving in, or some other millennial or multi-generational arrangement. You’ve probably already extended into the loft, out the back and maybe even underground. So should the chance arise to extend into next door too, why wouldn’t you do it?

There’s still stamp duty to pay, of course, but it…