Travel to the Cop26 summit was thrown into chaos on Sunday when the main train line from London to Glasgow was blocked by a fallen tree.
No trains could run to Glasgow from London Euston, the line's southern terminus, after strong winds knocked a tree on to electric wires. Talks between world leaders begin on Monday.
Passengers were told not to travel and entrances to Euston were closed to prevent overcrowding, disrupting travel plans for some of the 30,000 people expected to attend the summit.
Some were left looking for alternatives such as coaches or last-minute flights. Signal problems caused delays elsewhere on the 640-kilometre route.
"Due to the extent of the disruption for services heading north of London, we’re advising customers not to travel," train operator Avanti West Coast said.
Britain's other north-south rail artery, from London to Edinburgh, was also affected after overhead wires were damaged near the English city of Peterborough, causing delays.
Passengers were told their tickets would be eligible for Monday, the first day of the summit when UK Prime Minister Boris Johnson will open a conference of world leaders.