We were asked redesign this spacious maisonette apartment in Belgravia with complex planning regulations and Grade II listed status. The apartment, on the sixth floor of a building dating from 1830, was in poor shape and needed complete renovation. It was a semi-derelict shell. The roof space had been worked on without the permission of the estate the property belongs to, so we had to take all the changes down and start again. The transformation has been sensational. What began as a leaky, partially completed space became, after more than two years’ work, a light, open and fantastically elegant apartment.