A keen amateur pianist has commissioned Michael Trentham Architects to design a slim, one-bedroom house just large enough to accommodate his grand piano.

The piano will sit at the narrowest point of the wedge-shaped site, 2m wide at the rear and 5m on the street, which lies next to his south London Victorian terraced home.

“Music is a crucial part of his life,” says Trentham. “He will have just enough room to take the piano and enjoy the garden.”

From the street, the house appears one storey high.

A glass hall enclosure ensures the upper floor bedroom remains private, then a stair-case descends to the living area.

The first floor will appear to “float” as it will be detached from the walls on three sides and the gaps filled with glass.