RAILWAY companies have been accused of overstating the punctuality of their trains.

According to statistics obtained by the Sunday Times, more than half (55.3 per cent) of the 1,087 trains that arrived at Swindon Railway Station last week were delayed or cancelled.

Half of Great Western Railway services were delayed or cancelled – contrasting sharply with the firm’s own figures, which say that almost 90 per cent of their trains arrived on time.

The news will anger some passengers, who have faced long delays over past months caused by the electrification of the main line from London to Bristol.

The Swindon figure was calculated from Network Rail’s running data for the week Friday July 21 to Thursday July 27, derived from its signalling systems, and analysed by the Sunday Times.

The newspaper’s research show that almost half (47.9 per cent) of Great Western Railway’s services were cancelled or did not arrive at the station on time last week.

The statistics appear to contradict the railway firm’s own punctuality figures, shared on their website.

According to Great Western Railway, on average 85.8 per cent of the company’s High Speed trains arrived at their final station on time in the four weeks from Sunday June 25 to Saturday July 22.

Across all its services, 86.7 per cent of Great Western Railway’s trains ran on time in that period.

The main reason for the difference between Great Western Railway’s own statistics and the Sunday Times figure is down to measurement.

Train punctuality is tracked through the public performance measure (PPM). Officially, a train is deemed to have arrived “punctually” if it pulls into its final station within 10 minutes of the timetabled arrival time.

Rail companies have previously been accused of “padding” timetables – adding time in between the penultimate and final stops to ensure that the train arrives on time.

The Sunday Times counted any delay of up to a minute or more, measuring delays at every single station stop – and not just the train’s final destination.

A spokesman for Great Western Railway said: "Almost nine in ten of our services arrive within 10 minutes of the advertised time. However, we know how important punctuality is to our passengers. That is why we set ourselves challenging targets for improvement, and when we fall short of those standards, it is right that we compensate accordingly.

“We recognise that there have been significant infrastructure challenges on key parts of our network. Everyone at GWR and Network Rail is determined to see improvements, and we are working hard with Network Rail to help them deliver improvements for us. The Great Western network is currently undergoing its biggest period of investment since Brunel.”

The rail industry is moving away from the potentially misleading PPM measure.

The Rail Delivery Group, which brings together train operators and Network Rail, announced this month that they planned to adopt a station-by-station approach to measuring train punctuality.

Paul Plummer, chief executive of the Rail Delivery Group, said: “By adopting the most transparent measure in Europe, we want passengers to know that rail companies are putting an even greater focus on ensuring that trains are meeting the timetable, arriving to the minute and at stations along a journey.”