Hundreds of trains through London Paddington were cancelled and services are unlikely to return to normal until Wednesday morning.

Network Rail engineers have been trying to find out what caused the power cut at the signal centre in Slough.

Services on First Great Western, Heathrow Express, Thames Trains, and Virgin Cross Country had to be cancelled and passengers were advised to avoid travelling unless absolutely necessary.

'Ongoing delays'

Trains from the south were forced to terminate at Reading, where passengers were advised to use South West Trains to reach London Waterloo.

Don McKabe from Network Rail said the problem had now been fixed.

He said: "Services are returning to normal, apologies to anyone caught up earlier today.

"There will be some ongoing delays but we have been working hard to try to minimise them."