Train operator First Great Western has drastically improved its punctuality just five months after coming last in national performance tables.

Last month, 88.9 per cent of Thames Valley rush-hour trains were on time, just below its 92 per cent target, while 91.1 per cent of its long-distance expresses were punctual, beating the 90 per cent target.

At the end of last year, FGW was bottom in the Office of Rail Regulation's performance tables, with just 79.7 per cent of its trains on time in the last three months of 2007.

FGW's own figures showed its performance was even worse on peak services in the Thames Valley, with only 64 per cent of trains on time at the turn of the year.

Nationally, passenger train operators ran 86.9 per cent of trains on time in the same period. The rail industry has an overall national target for punctuality of 88.3 per cent.

FGW and infrastructure operator Network Rail implemented a joint performance improvement plan, supervised by the ORR, to cut delays.

FGW's chief operating officer Andrew Haines said: "We still have work to do and it is early days, but the performance figure for April of just over 90 per cent is evidence that our actions to improve performance are beginning to take effect."

"We need to ensure that we deliver this improvement consistently for our customers and are working hard to do so."

Zahra Akkerhuys, a spokesman for Oxford commuter group Ox Rail Action, said: "We welcome the improvements and want to give credit where it's due.

"What was a truly abysmal service has been turned around but these are one month's figures and we want to see the improved performance sustained in the long term."