The 300,000 sq ft fit-out project at the new 20 Ropemakers Street office tower built by Skanska will become the London HQ for the legal firm.

Mace and Overbury have also been in the chase for the prestige fit-out project, which is understood to be worth around £120m.

According to an Enquirer source, ISG is now the frontrunner to seal the deal, although the firm refused to comment on progress with the bid.

The 25-storey stepped office block is designed by architect Make to be BREEAM ‘Outstanding’ and WELL Building Standard Version 2 – Platinum.

Occupiable office space will cover 22 floors, with five accessible roof terraces.

The project is another major coup for ISG’s fit-out  arm in the capital, which is also understood to have picked up a £150m project at the end of last year to fit-out Google’s big UK headquarters in King’s Cross.

Both projects will get underway this year.