Capital gains: John Lanchester’s satire of London’s boom years is adapted for TV

When writing Capital, his novel set in a time of financial excess, Lanchester thought things couldn't get any worse. But 10 years on, amid ever-rising house prices and continuing City scandals, he is dismayed to find they did

When asked where he got his ideas, the late Terry Pratchett would confidentially tell his audience, "Well, there's this warehouse called Ideas R Us." That was a good answer, because it did two useful things: get a laugh and deflect the question. The truth is, it is hard to know where ideas come from.

A novel usually begins, in my experience, with a thought or image that won't leave me alone. In the case of my novel Capital, I became obsessed with a thought I had one day, looking out of the window at the permanent chaos of building work near where I live. In addition to the skips and builders' vans, the scaffolding and concrete mixers and basement diggers, there was a constant scrum of deliveries and services going to people's front doors. The thought that struck me was this: that the houses were like living beings, with needs and demands of their own. Instead of being the backdrop to people's lives, houses had assumed such economic and psychological importance that they had now become principal characters in their own right.

The moment I thought of as one of supreme obliviousness, an obliviousness that would never return, is back with us

Related: Guardian book club: Capital by John Lanchester