A new basement is down there with my worst ideas

Granted, our basement may not have exactly been part of a collapse like the one in Belgravia this week, but its joys are not what I'd envisioned when we embarked on the subterranean project back in the autumn of 2005.

It won't make you popular with the neighbours: you need space for a skip, sometimes two or even three, taking up precious parking space for six months. It's an eyesore: there's the unsightly, noisy conveyor belt and skip in the front. Expect to redecorate some of your neighbours' rooms when cracks start to appear.

But from inside the house, the actual digging-out work is stress-free and surprisingly quiet. We hired a top basement extension company and by Christmas we were running around a huge concrete waterproof box under our house. By Easter the transformation was complete.

With five of us plus the nanny in a four-bedroomed house, we weren't looking for a swimming pool or tennis courts or any of the other unrealistic expectations the people of Belgravia and Mayfair place on their beleaguered Victorian foundations. All we hoped to gain was a much-needed spare room plus a playroom for the children, which in years to come would be a teenage space for them to go and be moody and monosyllabic.

But although the writer Imogen Edwards-Jones, who lives at the other end of our street, says her newly built basement is the "the most marvellous thing in my entire life", my children seem to use ours sporadically. It is a good few degrees cooler than the rest of the house and my eldest's penance is to do his homework there, while the five-year-old declares it "spooky" and refuses to go down alone.

Worse, after it was completed, life underground didn't feel so watertight. This was a basement built for a climate somewhere like Egypt. When the heavens opened over W10, water from our glassed-in side return would pour down into a gutter by the lightwell and should have disappeared down the drain. Except it kept finding its way onto the ceiling of the room below.

The basement company returned and much lead was laid. When water began dripping through a light fitting, part of the ceiling was taken down. Mark, who built the kitchen extension (and who subsequently absconded to Spain), was blamed. More silicon was squirted and the ceiling proclaimed sealed.

But that wily H2O stuff is not so easily put off. At some stage the basement company got fed up with our pleas, so we called in Jerry the cockney builder. The cement gutter was the problem, he claimed, and a sealant "used in swimming pools" was liberally applied.

All was well for a year — until last week, when I made a rare visit to the land down under. Following a week of heavy rain, a wet mattress and a huge pool of water awaited me, dripping from not one but two light fittings. Because there hadn't been a "gale" during that week, the Axa insurance people refused to send an assessor. A new builder is about to rip the whole waterlogged ceiling down.

Even the spiders, in their £200,000 palace, won't be happy with that. You mess with Victorian houses at your peril.