All stations and spurs will be built but first section in central London will be complete in 2018 and unlikely to open to public before 2019

Crossrail will be delayed by at least a year, Building understands. The central section, which runs underground from Paddington to Canary Wharf, will open in 2018, a year later than planned.

All spurs and stations, including the threatened Bond Street stop will go ahead. The total cost has been reduced from £15.9bn to £14.9bn through value engineering.

The eastern and western sections of Crossrail then be completed “a matter of months” after the central section is completed in 2018, according to Transport for London Commissioner Peter Hendy.

“There’s not some subterranean plan not to develop them,” he said.

Construction is being “rephased” so that tunnels will be built before the stations. A senior insider at Crossrail said that the main tunnelling contracts would be put out to tender this year.

Kulveer Ranger, the Mayor of London’s transport adviser, said that Crossrail would not open to the public with just the central section completed.

“It will only open when the vast majority of it is complete - more than just the central bit,” he said.

This means that unless the central section is completed early in 2018 and the spurs follow within the year, passengers will have to wait until 2019 to use Crossrail, two years later than first claimed.

Boris Johnson said that construction would prioritise tunnelling over station building.

“We have rephased Crossrail to dig the tunnels before the stations. We will be able to evacuate the soil through the tunnel rather than using thousands of lorries through London,” he said.