A winner on the last major City office deal to be awarded this year is set to be announced by the end of the month.

Mace and Multiplex had been expecting to find out earlier this autumn who had won the job at 65 Gresham Street.

But a decision has slipped with the pair believed to be neck and neck for the job which is worth around £200m.

Outdoor workspace will be added to every floor of the refurbished building

Designed by Squire & Partners, the job for JP Morgan Asset Management is being described as one of the largest building reuse projects in the Square Mile.

The building was originally designed by Sheppard Robson and completed in 2001 but the new plans involve expanding it from 24,995 sq m to 37,767 sq m. The proposals include adding balconies, upper level amenity space and outdoor workspace to every floor.

Others working on the deal include cost consultant Turner & Townsend Alinea, project manager Opera, structural engineer Buro Happold, services engineer Atelier 10 and facade engineer Murphy Facade Studio.