Crossrail construction could be “phased” and this is likely to mean that the project opens in stages to the public

A programme of value engineering has also brought the projected cost of the project down below £15.9bn but individual companies working on Crossrail are in the dark as to what the overall budget is now likely to be.

One insider close to the project said that there could be “phased construction” that might lead to different parts of the network being opened in stages. Another source confirmed that Crossrail was likely to be subject to “phased completion” that would see certain parts open before others.

He said that station designers had cut costs over the summer and submitted their new estimates to Crossrail, who now had a revised figure below the original £15.9bn estimate – but had not revealed to firms what the new total figure was.

“A few months ago we were above [the £15.9bn total] and now we’re below,” he said.

The Evening Standard reported last night that Crossrail would be delayed by a year and would open in 2018.

Rob Holden, chief executive of Crossrail, did not deny that it would open a year later than planned.

“I’m not saying one thing or another,” he said.

“I can’t really say anything because it’s for the government to make an announcement as part of the comprehensive spending review. I’m waiting until next week.”