High temperatures have brought severe disruption to rail services.

Dozens of trains were cancelled or delayed across England on Wednesday morning because of problems caused by the extreme heat.

Temperatures hit 40C on Tuesday, the hottest on record in the UK, causing damage to overhead wires, tracks, and signalling systems.

National Rail has told customers to check before setting off on their journeys and to only travel if absolutely necessary.

It said on its website: “A huge amount of work has been completed overnight to fix problems with the track and overhead wires caused by the heat yesterday.

“Network Rail teams are continuing to work tirelessly to make the repairs so we can get services back up and running for passengers but there is still disruption to services throughout the day. So, for anyone travelling today, please take time to check before you travel.”

More than two dozen services departing from London King’s Cross and Euston were cancelled or delayed.

Services on the East Coast Main Line, the main rail artery connecting London and Edinburgh via Peterborough, Doncaster, York, Darlington, Durham and Newcastle, was damaged on Tuesday after a fire spread on to the track near Sandy.

The route between London King’s Cross and Peterborough is expected to remain closed until at least midday.

Provider Avanti West Coast said services from London Euston have been cancelled due to ongoing repair work following damage caused by fires in the Hatch End area on Tuesday.

All lines between Lancaster and Carlisle and lines in the Birmingham New Street area are blocked due to severe damage to the overhead electric wires.

There are no trains between London Euston and Scotland, no trains running north of Birmingham to Wolverhampton; and trains are being diverted via Northampton.

An Avanti West Coast spokesman said: “Train services are severely disrupted across our network as a result of damage to the overhead wires at multiple locations due to yesterday’s extreme heat. Network Rail is still at the sites carrying out repairs.

“Customers should make sure they check their journey before leaving for the station, and train tickets for yesterday and today will be valid for travel tomorrow. We’re sorry for the inconvenience this will cause.”

Network Rail said passenger numbers on Tuesday were around 40% lower than the same day last week.

Overhead electric wires were down in Rugby, Birmingham and Carlisle, leading to a number of trains being trapped and emergency evacuations of passengers.

Network Rail Wales apologised for having to close the Cambrian Line between Dovey Junction and Aberystwyth “due to extreme heat”.

No rail services were running into or out of London King’s Cross on Tuesday, and no Thameslink or Great Northern services were planned to run north of London all day.

East Midlands Railway was running limited services between Derby, Nottingham, Luton, Bedford and London, which were due to stop completely between lunchtime and 7pm – the hottest period of the day.