South West Trains say a problem at a level crossing between Barnes and Richmond means all lines will be blocked and services disrupted until around 6.30pm.
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Donald Trump is to visit the UK on July 13 and hold bilateral talks with Theresa May, Britain's ambassador to the US has said.
The Football Association has announced it has received an offer to buy Wembley Stadium.
The most hotly-tipped date is July 13, following the Nato summit which the president is due to attend in Brussels on the previous days.