Derwent Valley has let 50,400 sq ft (4,682 sq m) at its Johnson Building development in Hatton Garden, London EC1, to advertising agency Grey

Grey, which is part of Sir Martin Sorrell's WPP group, is paying an average rent of £35.32/sq ft (£380.18/sq m) for space on the lower-ground, ground, first, fourth, fifth and sixth floors of the 150,000 sq ft (13,935 sq m) building.

The advertising agency has signed a 15-year lease with a 10-year break clause and 16 months rent-free.

John Burns, managing director of Derwent, said: 'Johnson was designed to provide flexible space for multi-occupancy and we are currently in negotiations with a number of other potential occupiers for the remaining space.'

Pilcher Hershman, CB Richard Ellis and Mark Slim & Partners acted for Derwent; James Andrew acted for Grey.