Rail passengers faced some cancelled and altered services on Thursday morning in the wake of heavy rain overnight.
A National Rail statement said all lines between London Kings Cross / Moorgate and Stevenage, Hertfordshire are closed following “a number of incidents”.
“Trains may be cancelled, delayed by up to 90 minutes or revised,” the statement said.
“Major disruption is expected until 09:00.”
Customers have been warned not to travel on routes which usually run through Stevenage after damage to overhead electric wires resulted in the closure of all rail lines via the station.
Disruption has also been reported through Tulse Hill in Lambeth and Cheltenham Spa, as well as between Lewes and Wivelsfield in East Sussex and West Ealing and Greenford in west London.
Flooding had earlier affected rail lines at Burnham, Buckinghamshire and between Swansea and Llandrindod in Wales, with both incidents since cleared up.
It comes after the Met Office issued a yellow weather warning for rain across parts of south-east England from 4pm on Wednesday until 3am on Thursday.
Sunny spells are forecast for the east of England this morning, while some heavy and thundery showers could break out elsewhere throughout the day before easing in the evening.
Met Office meteorologist Aidan McGivern said: “A band of rain will clear by the start of Thursday and that will be followed by sunny spells and showers with low pressure never too far away from the UK.
“Some cooler weather, along with some chilly nights, are likely as we move towards the weekend.”
