Network Rail missed its punctuality target by half a million minutes last year but still recorded the best train performance for four years.

The rail group said delays fell by more than one million minutes to 13.7 million for the year to the end of March.

However, Network Rail had set itself a target of 13.2 million minutes.

A company spokesman blamed "two exceptional events".

"We lost 300,000 minutes in the blackout in south London last September," he said.

"And the heatwave last summer meant that we had to put up temporary speed restrictions. Without these two events we would have been pretty much bang on target."