We have been treating the third rail in the south of England with anti-icing solution and trains were running around the network overnight to keep the rails clear of ice as much as possible.
Additional people were used on the ground to respond to incidents and carry out regular inspections of the infrastructure.
We will continue to work closely with train operators throughout today to deliver the best possible level of service and apologise for any disruption caused to passengers.
For the latest information, passengers should check with National Rail Enquiries or their train operator before travelling.
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After a dry start, sunshine will become increasingly hazy as cloud thickens, bringing patchy light rain to some parts.
After a dry and bright start across the region, sunshine will become increasingly hazy as cloud thickens.
Showers soon dying out this evening to give a dry night with some long clear spells and light winds.