We have just finished work on this beautiful, contemporary penthouse in St John's Wood, one of thirteen apartments in a converted orthodox church. It's situated near the famous Beatles zebra-crossing, next to Abbey Road Studios.

The first thing we did was to declutter the main space, which came with two entrance doors and several internal doors which were dividing up this exceptional space. We were able to remove all previous internal doors and join the spaces on the main level into one. The shape of the space feels like half a cake, with identical towers either side of it which each house a bedroom and storage as well.

The high ceilings in the centre are now fully utilised with a curved steel mezzanine, clad with frameless glazing and overlooking the kitchen, living and dining area below. The frameless glazing follows down to the main level where you step onto a new walnut and oak staircase. The apartment has many levels, joined by light oak steps and protected by almost invisible frameless glazing.

The new kitchen comes with a wide Range cooker, incredible fridge/freezer drawers, an island unit with a wine fridge and full-height storage. A custom-shaped stainless steel worktop contrasts well with the adjacent concrete walls and splash backs.

Either side of the new kitchen, we designed concrete-clad bathrooms with fully lit ceilings made of plexiglass panels. The walls and flooring are made of real concrete panels, which give a cooling effect; while underfloor heating keeps the space warm. Both the ventilation and lighting are hidden above, and the ceilings allowed us to integrate overhead showers. In one of the bathrooms we built in the washing machine, set within beautifully detailed walnut joinery, and the other bathroom has a suave Laufen bath with mood lighting and Aquavision TV to help to unwind after a busy day.

When stepping up into the bedrooms, you can see how the bespoke, seemingly floating stairs take you up into the octagonal turret level above. These spaces are air-conditioned and, with two tall windows either side, have plenty of light coming in.

New walnut furniture was custom-designed throughout and provides storage in the often difficult-shaped spaces.