Great North Eastern Railway, which runs the high-speed link between London and Edinburgh, has previously trumpeted a 3 per cent improvement in punctuality, but has yet to meet the demanding targets set out in the company's passenger charter.
The railway's internal "Team Brief" document describes the performance as "disappointing" and says that in a "critical period" after Christmas, performance targets were met on just two days.
According to the briefing, passengers waiting for a train on the high- speed line over a four- month period from October last year found that only 62.5 per cent of services ran on time.
But under the passenger charter - which allows season ticketholders to be able to claim refunds for poor performance - GNER is allowed to claim that services within 10 minutes of their arrival or departure time are "on time". Even with the extra leeway, GNER did not meet its charter targets of 90 per cent.
In the two months from December last year, the company managed only 82.8 per cent under the passenger charter - which excludes delays caused by crime, vandalism and poor weather.
However, railway pressure groups said that the "flagship route should be delivering a premium service".
Jonathan Bray, a spokesman for Save Our Railways, said: "This railway benefited from pounds 500m of investment prior to its sell-off. Passengers expect, and are entitled, to a better performance."
A GNER spokesmansaid the service had improved, adding: "Under the industry measures, performance has got better." In the 12 months up to March, GNER says that using the charter measure 89.9 per cent of trains were on time - matching British Rail's performance.
The company is also planning to buy five new tilting trains to increase joinery times and will overhaul all rolling stock this summer to improve train reliability.Reuse content