Interest has surged since relaxation of planning rules last March, but technical difficulties often loom large

On a busy high street in Balham, south London, stands a boxy, beige-fronted building. Built in the 1940s, for decades the four-storey office block was home to hundreds of civil servants until Department for Work and Pensions officials moved out in 2020.

Now, Irene House boasts 77 one- and two-bedroom upmarket apartments with seven more homes inside a roof extension. It still has its art deco entrance and other features inspired by the building’s original interior, and represents a growing trend: to convert office blocks into homes.