The Enquirer understands that the deal to fit-out 5 Broadgate is now a straight race between ISG and Mace/Como.

Banking giant UBS will occupy the 111,000 sq metre scheme which is currently under construction with Mace as project manager.

Work started in April 2012 for developers British Land and Blackstone with UBS set to move in by the end of 2014.

UBS is now believed to be talking to the two firms with the fit out deal believed to be worth up to £135m.

Sources close to the project said ISG is edging ahead with a winner due to be announced in October.