The Enquirer understands that pay talks have discussed a figure of nearly £60,000 a year for full-time builders on the site.

Talks are currently ongoing between main contractor joint venture Bouygues Travaux Publics/Laing O’Rourke and the construction unions.

And the industry’s ongoing skills shortage means the unions are in a strong position.

One source close to the talks said: “This is the biggest construction site in the country and everyone wants to get it built on time.

“The unions know that and any pay deal will be better than the one at Heathrow T5 where everyone made sure people were paid industry leading rates to get the job done.”

But other sources said the current offer was a long way south of £60,000 as the contractors are expected to come back with more realistic numbers.

The source said: “If you rolled up all allowances and potential bonus payments then we are still not getting anywhere near £60,000 with the initial offer from the Tier One contractors.

“There’s a lot of talking still to be done.”