We understand that pay talks have set the bar at 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.”