Fashion mavens mark and robert

are used to turning convention on its head. They transformed their previous home by building upwards in a top-floor apartment, giving them soaring views over the City. In their new home, they took the opposite approach, digging down to create a new floor. Yet, in a feat of architectural alchemy, the result is not dissimilar: a flowing space flooded with natural light. ‘We wanted a basement extension that defied expectations – and we got it,’ says Mark.

The couple were searching for a property challenge, but also wanted somewhere that captured their imaginations. ‘This place has a quirky history,’ says Robert. The building had previously been a Victorian mission house, a ragged school for waifs and strays and a Salvation Army hall. ‘That was all part of its appeal.’

Going through library archives, Mark discovered that, until the 1890s, two Georgian houses had stood on the spot. ‘Then, all records of those houses disappeared – presumably because of a fire – and only recommenced decades later with a mission hall.’ By the Eighties, developers had chopped the space up into flats. Once Mark and Robert viewed it, the building had been converted back to a single home, ‘but of the featureless, white box variety – very Noughties,’ says Robert. Yet beneath its bland, boxy rooms lay the bones of an intriguing building and, more interestingly, a cellar.

The duo come from creative backgrounds – and have an eye for a good opportunity. Before succumbing to a love of interiors, Mark was a fashion buyer for major stores including Debenhams, while Robert was at Arcadia Group and also played a key role in launching asos.com. They transformed this place with the same ambition.

From the start, Mark was dreaming up ideas for the décor and surfaces, but to transform the building’s structure, the couple called on architecture firm Michaelis Boyd Associates. ‘We loved their work at Soho House hotels and they did a great job converting a friend’s basement, so they were the natural choice,’ says Robert. The excavation of the cellar facilitated the flowing lower-ground floor with double-height Crittall glazing on to the garden. ‘Incredibly, the most effective way to remove the earth was digging by hand and using an old-fashioned wheelbarrow,’ says Mark.

Upstairs, on the entry level, part of the floor space was cut away to create a generous void over the new dining area below. ‘Now, light flows not only down into the lower level, but across, into the living room and then up the stairs,’ says Robert.

The old staircase, with six cumbersome flights and three half landings, was replaced by a linear, streamlined version in dark wood and riser-free steps. It serves to draw the eye upwards, aided by a continuous run of bare brick wall. ‘We love how its pitted surface hints at stories of the building’s past,’ adds Mark. At the end of the entrance hall, a restored stained-glass window from the house’s mission days now casts its biblical message into a very different interior.

While the hallway bricks err towards a grittier warehouse vibe, the living room indulges a more luxurious feel, with a sandstone fireplace and an Italian chandelier providing traditional focal points. ‘We knew we needed to go big with the light in here, so this Seventies-inspired number is a glamorous centrepoint,’ says Mark. Plush velvets and a gentlemanly library corner with Sixties and Seventies art are the finishing touches in this comfortably sociable space.

Surfaces on the lower-ground floor tend towards earthier, natural textures, with worn-in leather, moonrock marble and a run of dark walnut cabinetry. Letting light shine on both living levels is that game-changing expanse of Crittall glazing. As a break from standard black metal frames, Mark opted for a dark bronze finish. ‘The look is still strong and graphic, but not quite as harsh as black,’ he explains.

Mark and Robert entertain a lot – partying was always part of the long-term aim for this home. ‘The spaces really come into their own when we have friends or family round,’ says Mark with a smile. It’s hard to believe that over a century ago, this home echoed to the sound of missionary sermons and children’s hymns. But Mark and Robert have seen the spaces deftly reworked in a way that both recalls the building’s past, but also sets a contemporary beat.

See more of the architect’s work at michaelisboyd.com. Find out about the bespoke kitchen at jacktrench.co.uk