Rain has returned to south-west England, bringing flooding and high river levels to areas already saturated by heavy downpours.
Christmas Eve was wet in parts of England, Wales and Scotland, with Wales and the South East of England set for a very wet Christmas Day.
The rail network in the South West of England suffered major disruption.
Operator First Great Western advised customers not to attempt to travel west of Taunton in either direction.
The Environment Agency has issued about 160 flood warnings and more than 260 flood alerts for all regions in England and in Wales, with most in place across the Midlands and south-west England.
Up to 30mm of rain was expected on Monday in south-west England, where some 57 of the flood warnings remained in place into the evening.
In Scotland, 19 flood warnings are in place affecting Aberdeenshire, Caithness and Sutherland, Dundee and Angus, Tayside and the Borders.
Advanced weather warnings have already been issued for 26 and 27 December, advising that heavy showers on saturated ground across the UK could lead to localised flooding.
Christmas Eve on the rail network saw services from London Paddington towards Exeter and the West of England terminating at Tiverton, with limited road transport continuing to Newton Abbot via Exeter St Davids.
First Great Western said trains were unable to operate between Tiverton Parkway Station and Exeter St Davids, and between Exeter St Davids and Newton Abbot.
Services from Penzance and Plymouth, towards Bristol Temple Meads and London Paddington, are terminating at Newton Abbot, again with limited road transport on to Tiverton via Exeter.
It says the road replacement service is limited "as this is being hampered by flooded roads and only a reduced number of vehicles being available".
The closed section of line is not expected to reopen until Friday.
There are delays to journeys between London and south Wales, with a diversion to avoid flooding at Swindon adding about 45 minutes to travel times.
Flooding Minister Richard Benyon told BBC Radio 4's The World At One: "I'm really impressed with the way the emergency services, the Environment Agency, the local authorities are working together, and humbled by the incredible community spirit in places like Braunton (in Devon).
"There are going to be houses flooded in the future, we have just got to be better at warning people, we have got to be smarter at how we build defences (and) what defences we build.
"Government is doing a lot better, we have always got to learn from every single flood and realise it's the most miserable experience for people to have their homes flooded, and it's very damaging to the economy as well," he added.
'Coming home to no home'
Athol Innes, a Stonehaven resident working for an oil company in China, contacted the BBC News website:
"My house is totally flooded, sewage and oil. Gutted. It's still to hit me really.
"I am only getting information through the local Stonehaven Facebook page and the BBC Scottish news as I am working in China for a oil company and can't get flights till Thursday."
He is "worried as I have no accommodation to go home to. My house is in a terrible condition with the water and mud. The whole house, including the garden, is just ruined.
"It's still to hit me really. I have a friend that looks after my house when I am away on business, he only got access after 1pm yesterday and told me the sad news that my home is ruined.
"(He) keeps an eye out for any flood warnings and places sandbags against the doors when required; these failed.
"I am having to stay at the local hotel in Stonehaven when I arrive back in the UK at 1030pm on Thursday.
"Just can't believe this has happened. It's now the case of dealing with the insurance companies now and having all that added stress...
"It's coming home to no home that's hard-hitting."
Professor David Balmforth, a flooding specialist at the Institution of Civil Engineers, told the programme: "We know in the future global warming will make the sorts of flood events we have seen here become much more frequent and much more severe so some of the older (flood) defences which might have been fit for purpose at the time may not be quite so effective in the present day."
Environment Agency director of operations David Jordan said: "Flooding is devastating at any time of year, but it is particularly hard at Christmas time, and our thoughts are with those who will be out of their homes over the festive period.
"Although the rain is set to ease a little in the coming days, the ground is still very wet and river levels remain high, so we would ask people to keep up to date with the latest warnings and stay prepared for flooding."
He also reminded people not to walk or drive through floodwater.
A number of other key routes - including the A1(M) in Hertfordshire, the M6 in Cumbria and Staffordshire and the M5 near Bristol - were also struck by weather-related delays.
Reduced train services were operating on the West Coast line, and flooding had also disrupted CrossCountry, East Midlands Trains, First Great Western (FGW) and First TransPennine Express services.
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