July's reduction is said to be the 10th month of improvement

The company says this confirms a 10th consecutive month of improvement since it took over direct control of track maintenance.

The July figures mean around 84.5% of services ran on time but the rail operator acknowledged there was still "much work to be done".

Wessex and East Midlands saw the biggest improvement with delays down 50%. The Thames Valley fall was 36%.

Deputy chief executive Iain Coucher said the improved performance was down to changes the company had made, including taking rail maintenance in-house and working more closely with train operators.

A Rail Passengers Council spokesman said of the latest figures: "I think it's very positive that this is the 10th month of improvement as it has been a fairly static performance for several years.

"Trains are running on time more of the time but for the vast majority what they are not seeing is a vast improvement in performance.

"But they are aware there is a lot of work being done and they are starting to see changes."

Network Rail replaced Railtrack in 2002 and the following year announced that all maintenance work would be brought back in-house.

This had previously been sub-contracted to private engineering companies, and standards had been criticised.