In the 30 months since the Elizabeth Line opened – years late and billions over budget – the east-west line through London has become the most important piece of transport infrastructure in the UK . Britain’s three busiest rail stations are all on the Elizabeth Line . But after two days of chaos due to a botched software upgrade , which caused the cancellation of hundreds of trains, commuters face a further month of disruption.

The RMT union has announced industrial action by “control room grade members” working for the Elizabeth Line after rejecting the company’s latest pay offer. The union is seeking improvements to holiday entitlement and reduced working hours. A two-week overtime ban begins on Thursday 5 December .

From the final trains on Christmas Eve to 30 December, no trains will run west from London Paddington due to work on the HS2 project at Old Oak Common. The following day RMT members will resume industrial action with a 24-hour strike beginning at 9pm on 31 December. The aim is to disrupt New Year’s Eve celebrations in central London.

The RMT’s general secretary, Mick Lynch, said: “Our members play a vital role in running the Elizabeth Line and their demands for fair treatment on working hours and leave remain unmet. “The current offer falls short, and our members are determined to secure a fair deal.” The union has called for talks with Elizabeth Line management.

If the industrial action goes ahead and causes disruption, millions of Decemb.