Only a third of passengers are “very confident” of being able to buy the best value train ticket

The rollout of cheaper train fares is at risk because of a Whitehall row over the biggest shake-up of the railways in 25 years, The Times has learnt.

A review of the rail industry has been delayed after a clash between the Treasury and the Department for Transport (DfT) over the cost of reforms.

The analysis, led by Keith Williams, the former chairman of British Airways, had been due for release as a white paper last autumn, but ministers will now only promise that it will be published by the end of July.

It is understood that the delay is due to concerns over the financial implications of an overhaul of the fares system. Mr Williams said he wanted “simplified fares and ticketing” to stop