A fallen tree caused severe rail disruption between London and Cambridge, with disruption along the Hertfordshire-Essex border.
Greater Anglia trains in and out of London Liverpool Street were cancelled or stopped short throughout Saturday, June 25, with no Stansted Express trains between Stansted Airport and the capital.
The tree fell on the line at Harlow Mill.
The disruption, which began at around 8.20am, fell on the same day as RMT Union strikes impacting Greater Anglia and Network Rail.
A Greater Anglia spokesperson said: "Essex County Fire & Rescue service has advised us of a fallen tree that had caught fire on the overhead electrical wires near Harlow Mill.
"Network Rail response teams are on site and working to safely remove the tree and inspect the railway of any damage caused."
A limited rail replacement bus is running between Broxbourne and Bishop's Stortford, where trains could not run.
The RMT Union strikes, which began on Tuesday, June 21 and end today (June 25), impacted 13 railway companies - including Greater Anglia - and Network Rail. Reduced timetables were put into place to accommodate staff shortages.
Thameslink and Great Northern staff are not on strike, but its service between Cambridge and London King's Cross is running to a reduced timetable.
Greater Anglia tickets were accepted on Thameslink and Great Northern trains.
There was no strike action on the London Underground network, and tickets were also accepted on Transport for London trains between Liverpool Street and King's Cross.
Due to strike action, the final train from Cambridge to King's Cross departed at 5.24pm today (June 25).
The final King's Cross to Cambridge train left at 5.32pm.
All Greater Anglia trains finished their journeys at around 6pm, with no trains at all on on branch lines, including the Hertford East line.
Refunds and delay repay options may be available for passengers affected by disruption, rail firms have said.
The disruption may have affected passengers travelling to music events throughout London.
These include Ed Sheeran at Wembley, The Red Hot Chilli Peppers at the Olympic Park near Stratford, or the Rolling Stones at Hyde Park.
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