Rail watchdogs think "complaint fatigue" may explain a drop in passenger complaints.

The Rail Passengers Committee for Southern England said the number of complaints it received last year dropped by 16 per cent.

Committee secretary Mike Hewitson said: "We're wondering if people have just got fed up of complaining.

"After all, once you've written two letters saying 'My train was late', what's the point in writing a third?

"Whatever the reason, it is surprising because the levels of performance have not improved. Up to Christmas it was very poor indeed."

Mr Hewitson said he would be extremely concerned if anyone thought complaints were down because services were improving.

The number of complaints to the committee dropped from 1,975 to 1,656 last year, the lowest for five years.

Mr Hewitson said: "There must be an element of complaint fatigue, particularly with season ticket holders who perhaps cynically think, 'They wont do anything so why bother?'"

Committee chairwoman Wendy Toms said between November and December last year, peak-hour services reached a new low with less than half the trains running on time in the worst affected areas.

Some trains were even less punctual than in the four weeks after the Hatfield train crash the previous year, when speed restrictions brought chaos to the railways.

Ms Toms said: "Only Connex South Eastern, out of the three biggest train companies in our area, actually managed to reach peak-hour punctuality targets on mainline services at least some of the time.

"The Public Performance Measure, which records train performance every day, showed most train companies' performance veering wildly."

Connex South Central and South Central - the franchise was transferred to Govia in August - received the second largest number of complaints, 433. But this was a dramatic drop on the previous year of 707. Connex South Eastern topped the list with 536 complaints, The largest number of complaints were about train performance and the quality of journeys.

Other complaints concerned stations, the standard of service and discontent with compensation when things went wrong. There were also 117 complaints about the responses given by train companies to complaints.

Ms Toms said the committee would be asking the train companies what they were planning to do to improve services.

The Southern England Rail Passengers Committee is part of the Rail Passengers Council set up by the Government to protect passengers' interests.