Richard Allan, Deputy MD, Northern, said: “The RMT’s announcement of yet more strike action is disappointing and frustrating. This will be a blow for our customers.

“It comes despite Northern proposing and entering into a joint working party with RMT on the future of the on-board role. We have agreed a terms of reference for those talks, agreed to discuss the RMT’s preferred outcome first and then held four days of talks with RMT in recent weeks. A further day of talks has also been proposed for Friday 17 August."