An Irish property firm, currently developing new offices in one of London’s best locations in the West End, has secured the highest rent ever paid in the city from a billionaire art dealer.

The deal for a 3,000sq ft floor at Green Property's 8 St James's Square development at £185 per sq ft smashes the previous record for London offices set in 2007, just before the global financial crisis struck.

The offices have been rented, according to the London-based Property Week magazine, as the private family office for art gallery-owner Helly Nahmad, who owns a £2 billion modern and impressionist collection, including Picassos.

The 65,000sq ft offices were completed in February, with each floor let individually. The grade II-listed Lutyens property next door is being restored by the company and returned to a private, eight-bedroom family residence.