Thor Equities, the US private equity firm, has let a prime retail unit at 1 Dover Street in London’s Mayfair to Caffè Concerto at a record rent for the street.

The company has let the 2,600sq ft unit at £500 per sq ft.

Joseph Sitt, chief executive of Thor Equities, said: “This new letting reflects Thor Equities’ active investment strategy in European high street retail areas including Mayfair, one of London’s prime luxury growth markets.”