Signalling problems sparked angry scenes at Oxford and Didcot railway stations today after trains were cancelled, leaving hundreds of commuters stranded.

Early trains between Didcot and London Paddington were cancelled and services from Oxford to London, Worcester and the north were also hit.

To make matters worse, First Great Western's supply of replacement buses was severely reduced due to the demands of race goers travelling to Royal Ascot.

Technical problems emerged shortly after 5.30am and were not solved until 8.30am.

Services finally returned to normal around midday.

A Network Rail spokesman said: "At 5.40am, a power surge in the Swindon area knocked out signalling along the line. Finding out why that happened will be the focus of our investigation."

At Didcot Parkway, hundreds of passengers milled around, as all train services were affected, and the 7.48am, 8am and 8.30am from Didcot to London Paddington were cancelled.

Scott Johnson, 27, from the Ladygrove estate in Didcot, who works as a civil servant in central London, was caught up in the chaos.

He said: "I arrived at 6.20am to find that there were no trains anywhere - to London, Wales, Bristol or Oxford.

"I had a meeting at 1pm and needed to get into the office early to prepare for it.

"This is an absolute piece of nonsense - maybe it is Network Rail's fault - but First Great Western should have better back-up plans and I think they have been given enough chances."

First Great Western spokesman Sue Evans said: "We urged Network Rail to rectify the problems as soon as possible.

"Some Oxford passengers travelled to Banbury to take a Chiltern Railways service in London Marylebone and their tickets were valid on those trains.

"Ascot and the school run meant an unusually high demand for the replacement buses we usually call on, but buses were laid on from Oxford, Didcot, Swindon and Reading.

"We apologise for the inconvenience."