No trains are running in or out of London Paddington as mourners descend on London and Windsor.
No trains are running in or out of London’s Paddington station, causing severe disruption for numerous mourners planning to watch the Queen’s funeral.
All lines between the west London station and Reading have been blocked since 06:30 BST due to damaged overhead electric wires, Network Rail said.
Great Western Railway (GWR), Heathrow Express and Elizabeth line services have all been affected.
Network Rail has warned services will be disrupted for the rest of the day.
No trains are able to run between Slough/Heathrow Airport and London Paddington, affecting people trying to travel to both London and Windsor.
The Queen’s funeral is taking place at Westminster Abbey, but central London viewing areas for the procession closed at about 09:30 due to overcrowding.
Passengers on a severely delayed Paddington-bound train were told by a member of staff on the public address system: “My sincerest apologies for the delays on such an important day for the country.”
One person wrote on Twitter: “I’m stuck on the train for two hours. Got up at 4am to get to Windsor early for the viewing. Absolutely horrible service.
“Barely even caught this train because nobody at Paddington knew which one it was. Sure didn’t expect this dismal service.”
The damage to the overhead wires happened at Hayes and Harlington station.
GWR said Chiltern Railways, Transport for London (TfL) and Southern Railway were taking passengers via any reasonable route until further notice.
Tickets are also being accepted on London Underground, London Buses and First Berkshire between Slough and Reading, as well as on South Western Railway services between London Waterloo and Reading.
On a train to Windsor
Maria Zaccaro, BBC News
Disruptions affecting trains to London and Windsor are not putting people off.
Dozens are still determined to get to Windsor to pay their respect to the Queen.
Several trains from Reading have been delayed as railway lines between Slough and Paddington are blocked due to damage to overhead electric wires.
Darren Long, 51, left his home in Lincoln at 04:30 hoping to be in Windsor by 09:00. But now he will not be there until later in the morning.
Passengers from Reading are being asked to change at Staines before getting on another train to Windsor.
But Sue Furness, 77, from Reading, says the delays are not putting her off.
“It is all part of the day. I just want to go,” she says.
She and her daughter Sindi Dumanowska, 55, are travelling together and say being in Windsor will be just a way to pay their respect to the Queen and thank her for her years of service.
A Network Rail spokesman said: “We are very sorry for the disruption which we expect to continue throughout the day.
“We are working hard to get services running as soon as possible and passengers are strongly advised to check before they travel.
“We will continue to update passengers as the situation develops.”
Lines between Reading and Newbury have also been closed after an incident on the line, causing some GWR trains to be diverted and further delaying journeys to the capital.
The issues come during one of the UK’s biggest transport operations as mourners descend on London and Windsor.
