Members of the RMT union are to be balloted for possible strike action over pay, in a move that could see as many as 10,000 staff go on strike.

If the strike were to go ahead it would see substantial disruption across the entire London Underground network.

The RMT confirmed that it has rejected a pay offer from London Underground worth 2.5% — the same as the Retail Price Index in February 2019.

The RPI stood at 2.5%, and although no longer recommended by the Office for National Statistics, they still calculate it as it is often used in contract negotiations, such as by London Underground.

The preferred index for use by the ONS is the Consumer Prices Index which also includes owner occupiers’ housing costs (CPIH) and council tax, and that stood at 1.8% in February 2019, so by the ONS calculations, a pay rise of 2.5% would be an “above inflation rate” offer.

However, the London Underground also limited the pay rise to a one-year deal, so that it will need to be renegotiated next year, and said it was conditional on other requests, such as a shorter 32-hour working week, and all CSA2 staff being promoted to CSA1, being removed from the discussions.

The RMT and London Underground were engaged in 5-days of talks over the pay settlement last week, and the RMT’s negotiators have since voted unanimously to recommend that the pay and conditions offer be rejected.

RMT General Secretary Mick Cash said “The union has made it clear that we are looking for substantial improvements in pay and the working conditions for our members who work round the clock to keep London moving and that we are prepared to fight to secure those objectives.”

“RMT’s negotiating team has wholly rejected the pay offer from London Underground management and that position has now been endorsed by our executive. As a result we will begin preparations for an industrial action ballot and the ball is firmly in LU’s court to come back with an improved offer.”

He also confirmed that planning for a strike ballot is now underway.

This is all taking place at a time when TfL is under heavy pressure to cut its operating costs due to a mix of the scrapping of the central government grant, declining passenger numbers, and the Mayor’s fares freeze.