“It is not uncommon, when introducing new trains on an existing network, for there to be some teething problems,” Baroness Sugg said in a Lords Written Reply on September 20.

Baroness Randerson (Liberal Democrat) had asked about the technical problems affecting the Azuma trains, and which organisation had made the decision to order them.

Sugg said that because new trains sometimes have teething problems: “This is why time is set aside to identify any issues as far as possible before the launch of passenger service. Hitachi and Network Rail are working together to resolve these issues with the aim of getting these trains ready for passenger service.”

She said the full benefit of the introduction of the 65 Class 800/801 Azumas will be seen when all the trains are in traffic, although she did not provide a specific date for that.