A points failure at Hitchin and a signal fault at Potters Bar caused severe disruption to trains between London and Peterborough.
Thameslink, Great Northern and LNER passengers from London King's Cross faced delays due to "a number of incidents" at around 3pm today (Tuesday, May 17), according to National Rail Enquiries.
Disruption ended at around 10pm today.
A Thameslink statement read: "Please travel later this afternoon/evening if possible, and if you do travel, please allow plenty of extra time to complete your journey.
"Be aware your journey may involve several changes to your planned route.
"A major signalling system fault has been reported in the Potters Bar area.
"This is disrupting all trains between Stevenage and Finsbury Park on the route through Welwyn Garden City.
"Trains are likely to be cancelled, diverted away from the area or revised to complete only parts of their normal journeys.
"For trains that are already on this part of the route, we expect there will be severe delays.
"Staff have also been advised of a points issue at Hitchin."
Thameslink and Great Northern trains between London and Peterborough or Cambridge ran via Hertford.
Trains between London and Ely or King's Lynn only ran as far south as Cambridge, and did not travel to London.
Stopper trains between Cambridge and London King's Cross, via Royston, ran between Cambridge and Welwyn Garden City only.
Some trains could not stop at Hitchin.
"If you require Hitchin, please travel on to Stevenage, and travel back to Hitchin on a train in the opposite direction," a Thameslink and Great Northern spokesperson said.
LNER said some of its trains were delayed by around 20 minutes due to the disruption.
Passengers on LNER trains also faced delays between Grantham and Newark North Gate due to safety checks, the company said.
LNER said its passengers could travel on Thameslink or Great Northern trains at no extra cost.
According to National Rail Enquiries, Thameslink and Great Northern tickets could be used on:
- Greater Anglia between Cambridge and London Liverpool Street
- LNER via any reasonable route
- London Buses on any reasonable route in central and north London
- London Overground via any reasonable route, including at Highbury and Islington
- London Underground via any reasonable route
- Arriva buses routes 55, 97, 98, 100, 101, 301, 302 and 724 in Hertfordshire
- Uno buses 601, 602, 610 and 653 in Hertfordshire
Join our Cambridgeshire Travel Information group on Facebook for all the latest traffic news in Cambridgeshire, or our Hertfordshire Hertfordshire Travel Information group for the latest updates in Herts.
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