Eurostar passengers face major disruption after a protester caused trains to and from St Pancras International to be suspended.
British Transport Police (BTP) said a man had been in “a precarious position” near the station since Friday evening.
Southeastern services heading towards St Pancras from Faversham and Margate have also been affected.
A man, 44, has been arrested for trespass and obstruction of the railway.
BTP confirmed eyewitness reports the man was waving an English flag.
It follows a day where thousands of people protested in central London over delays to Brexit.
Power to the overhead lines was switched off, so trains could not enter or leave St Pancras.
Shortly after 11:00 GMT, National Rail said Eurostar services started running again – but warned passengers to check before they travelled.
A National Rail statement said the protester spent the night on the railway viaduct that crosses the high-speed lines just outside the station.
He has now been removed and overhead wires have been recharged to allow services to resume, it added.
Passengers on Southeastern have been warned “alterations and cancellations” will remain in place for the near future.
They were previously advised to travel to Victoria or Charing Cross stations rather than St Pancras.