The internet giant has already agreed to take 242,800 sq ft of space at the developer’s nearby Rathbone Square scheme which is due for completion in late March.

Facebook was also given first option on taking space at Oxford House where main refurbishment work is yet to get under way.

In a trading statement to the City today Great Portland Estates said: “At Oxford House, 76 Oxford Street, W1, our 88,200 sq ft major mixed-use refurbishment scheme, Facebook have chosen not to exercise their right of first offer to occupy the 55,700 sq ft of office space.

“Dependent on market conditions, we expect to be able to commence construction during autumn this year although the development team continue to look for opportunities to improve the design of the currently consented scheme.”

The developer’s other scheme in the near-term pipeline is at Hanover Square in west London where demolition is now complete.

The company said: “Negotiations with Crossrail are ongoing to allow further access to the site, such that should market conditions be supportive, we can commence elements of the construction ahead of completion of the station structure by Crossrail in 2018.”

The longer term pipeline includes 14 as yet uncommitted schemes covering 2.4m sq ft.

The developer said: “These schemes provide an extensive pool of development opportunities, stretching into the early 2020’s, giving GPE a significant platform for organic growth into the next property cycle.”