For years, every day on his way home from work, Christian Keesing passed a vast empty unit within the foot of the Grade II-listed Barbican tower block he lived in.

“I’d probably gone past it at least a thousand times, until I had the idea,” Keesing said. The idea was to buy the four-storey space – which had lain empty for almost 50 years – and transform it into a vast and unique home at the bottom of the 43-storey Cromwell Tower in the 1970s brutalist complex.