Spanish train driver Francisco Jose Garzon has been discharged from hospital and taken into custody, said interior minister Jorge Fernandez Diaz.
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Duncan Jones tweeted: "1 month since dad died today. Made this card for him at Christmas. Due in June. Circle of life. Love you, granddad."
More than 10 days after his body was found, Richard Cole's family claim they are still in the dark over the circumstances of his death.
A cold and frosty start, then staying largely dry with plenty of sunshine.