Construction of a 51-storey skyscraper in Shoreditch has been stalled, after a deal fell through to let a third of its office space to a law firm.

CMS Cameron McKenna has pulled out of talks to pre-let 200,000 square feet of the �485 million Principal Place scheme, which Anglo-French developer Hammerson was due to begin building in April.

The development caused controversy when the original 2008 plans involved the destruction of the Light Bar, housed in a 19th century electricity substation in Shoreditch High Street.

A campaign forced Hammerson to revise plans but local heritage group Open Shoreditch still raised concerns that the development would encroach into a unique heritage area.

Planning permission was granted in 2009 for three skyscrapers containing offices, a hotel, 191 private flats and 50 affordable homes on the site between Norton Folgate, Curtain Road and Worship Street.

But the economic climate forced developer Hammerson to go back to the drawing table for what was dubbed Bishop’s Place.

Re-christened Principal Place, the 51-storey residential tower was redesigned and the height of the office building reduced from 37 to 16 storeys, while more public open space was allowed on Norton Folgate, and planning permission was granted for the second time last July.

Concern was raised Hammerson would be unable to find office tenants in the economic climate, but CMS Cameron McKenna LLP expressed interest in making the site its new head office location.

But now they have postponed their decision to move from Aldersgate Street where their lease expires in 2015 “until market conditions are more stable.”

On Monday Hammerson’s Chief Executive David Atkins said in a statement: “I have consistently said that in current conditions we would not expose our shareholders to excessive risk through building London offices on a speculative basis, which remains our policy.

“We have made good progress with the design and planning of Principal Place over the last six months, which I am confident will further improve its appeal to potential occupiers, and we continue actively to seek office tenants.”