Having lived on the opposite side of the road for some years, our client acquired this large property in West Hampstead with the intention of modernising as well significantly extending. The house was built in the1930s in the ‘arts and crafts’ Hocroft Estate. On the street it was 2 storeys plus loft floor, dropping an extra storey to a lowered south-facing garden at the back. With playing fields at the bottom of the garden, our client wanted to explore the potential of a design that was more sympathetic to the site and opportunities in terms of levels and relationships to the landscape. Our proposals did this by moving the main living space into the basement, with 4 metre high ceilings, full-height glass doors and skylights, to make a robust relationship with the garden and new pool house whilst giving lots of natural light. With the rear extension making a much deeper floorplan than before, we had to work hard to get light into the middle of the house. Our solution is a new steel central staircase rising in a glass-topped atrium that drops open-plan from a glass-sided entrance hall or climbs in sweeping curves up to the bedroom floors. At the very top, the expanded loft floor has new bedroom space with 3 large dormer windows giving views over south London. By extending the upper floors by 3 metres rearwards, and the garden level extension by 4 metres, then building a swimming pool on the back of that with a new basement underneath everything,