Mr Shuttleworth said West Coast will continue to lobby the ORR for an extension to an exemption from the central-locking rule that had been in place for the previous two decades.
He said: “We either press for an exemption for the Mark 1s, fit central door locking or simply not use them again, which would be a pity.”
The ORR has said Mark 1 coaches aren’t safe because passengers could open doors while the train is moving.
Mr Shuttleworth argued that stewards on the Jacobite bolted each door after passengers had boarded, making the train perfectly safe.
Mark 1 carriages are in everyday use on dozens of private heritage railways across Britain. However, running speeds are limited to 25 mph, meaning the central locking rule doesn’t apply. The Jacobite operates at up to 40 mph.
The newly acquired carriages will be moved from the Riviera’s base at Burton-upon-Trent to West Coast’s headquarters in Carnforth, Lancashire, which was once home to the Flying Scotsman.
It’s not clear whether they’ll be repainted from a blue and grey colour scheme into West Coast’s trademark maroon, which replicates the British Rail livery of the 1950s.
The Riviera purchase doesn’t offer a complete solution to West Coast’s problems: the way the fleet brakes make them incompatible with some of the company’s steam locomotives. However, so-called Black Five locomotives used on the Jacobite can haul the stock.