The £115m facility is believed to be the first of its kind for any significant speculative residential development since the credit crisis. It is being provided by a syndicate of three banks – Santander, HSBC and Investec.

The scheme’s original construction cost was estimated at £150m but Heron is believed to have driven a hard bargain with contractors.

Mace was left in a two-horse race for the job with McAlpine but sources at the losing contractor told the Enquirer they could get “nowhere near” the winning price.

Marketing of The Heron – which will be a slender 36-storey tower providing luxury living space next to the Barbican -began in March 2010 and over 40% of the 284 apartments have already been pre-sold.

Jonathan Goldstein, Deputy Chief Executive of Heron International, said: “The consortium’s decision to provide the financing at this stage of the economic cycle is a validation of the progress we are making on site which will provide much needed, first class living accommodation in the heart of the City of London.”