The architect behind the planned tallest building in the City of London has said a slowdown in projects sent the firm into the red last year, warning the situation would not improve by the time its next financial year closes in July.

Eric Parry Architects’ 73-storey tower at 1 Undershaft (pictured) was given planning 18 months ago and will be close to 305m tall when built.

But the firm said a “slowdown in progress of some projects, together with a bunching of projects coming to completion during the year, has led to a reduction in turnover and profit”.