MacCormac Jamieson Prichard's plans to revamp the BBC's central London headquarters have been held up by a legal challenge from a powerful local landowner.
Howard de Walden Estates is seeking an injunction to prevent work going ahead on the £400 million flagship Broadcasting House project.
The company claims to hold a restrictive covenant, drawn up in the 1930s, which prevents the BBC from raising the height of the building.
Simon Baynham, Howard de Walden Estates' managing director, said the eight-storey scheme would have an adverse effect on its property on Duchess Street to the North of Broadcasting House, which would reduce rental values.
An injunction hearing is set for 17 February, but Baynham said his company would be willing to back down if the corporation offered adequate compensation for the damage.
The BBC confirmed that it had received the legal challenge and that it was in discussions to resolve the issue.
MacCormac Jamieson Prichard won planning permission for the project in July (AJ 4.7.02), after the scheme was rejected first time around on grounds of excess height and bulk. It will provide the world's largest live broadcast newsroom and includes the creation of a new public piazza between Portland Place and Hallam Street to provide exhibition and performance spaces.