The firm has spent the past year working alongside the developer under a pre-construction services agreement to refine the engineering and delivery strategy for the £200m scheme.

Confirmation of the main works contract paves the way for work to start next year, following completion of demolition and enabling works by McGee.

Designed by AHMM, the 236,000 sq ft, nine-storey project will provide premium office space alongside shops, restaurants, and 17 flats.

A key feature of the project is its low-carbon construction strategy.

Around 2,000m³ of structural concrete will be cut out of the existing building and reused in the new structure using the Piecewise Reuse of Extracted Concrete in new Structures (PRECS) method, cutting embodied carbon and reducing waste.

The scheme is targeting BREEAM Outstanding for the office accommodation, BREEAM Excellent for the retail and residential elements, LEED Platinum certification and a NABERS rating of at least five stars.

Richard Baldwin, director of development at Derwent London, said: “After a one-year pre-construction services agreement, we are pleased to be working with Multiplex once again to deliver 50 Baker Street following our successful White Collar Factory and 80 Charlotte Street redevelopment projects.”

Callum Tuckett, managing director at Multiplex UK, said: “50 Baker Street is a significant project for London, bringing together high-quality workplaces, homes, retail and community spaces within one of capital’s most established districts.

“The project also represents a valuable opportunity to advance circular construction in the UK.”