The trespasser was eventually found hiding up a tree in Hertfordshire after causing disruption to rail services (Pictures: Getty/Twitter)

A trespasser responsible for at least 20 train cancellations and hundreds of delays was found hiding up a tree in Hertfordshire.

The individual got onto the East Coast mainline – which runs from London to Edinburgh – on what was a busy weekend for passengers.

British Transport Police deployed helicopters and dog teams to locate the person in Potters Bar, while Great Northern, LNER, Grand Central and Thameslink all suffered delays.

A Network Rail spokesperson said: ‘The individual has been safely removed from the railway and services are up and running again.’

The delays came ahead of a planned 24-hour tube strike tomorrow, that is set to close many stations across central London.

Which train companies could be impacted by the RMT strike?

RMT members from 14 organisations have voted to take part in a massive strike over pay, jobs and conditions this summer.

If it goes ahead, it’s expected to be the biggest walkout of its kind in modern history and could result in empty shelves in supermarkets.

Network Rail staff, who are responsible for signalling, are taking part, as well as workers from these 13 different franchise operators:

Chiltern Railways
Cross Country Trains
Greater Anglia
LNER
East Midlands Railway
c2c
Great Western Railway
Northern Trains
South Eastern Railway
South Western Railway
GTR (including Gatwick Express)*
Transpennine Express
Avanti West Coast
West Midlands Trains

*Voted against strike but in favour of more limited industrial action.

Passengers have been advised to avoid travelling on the London Underground all through Monday and before 8am on Tuesday unless it is ‘necessary’ to do so.

For those who have to travel, Transport for London have told customers to do so after 8am tomorrow and to complete their journeys by 6pm that day.

The industrial action has been taken by members of the Rail, Maritime and Transport Workers (RMT) union amid a dispute over pension plans and potential job cuts.

RMT general secretary Mick Lynch warned he ‘can’t see a way out from the strikes’.

More: London

RMT members from Network Rail and 15 train operators have agreed to walk out this summer over work conditions, with the date of the strike predicted to take place in mid-June.

Mr Lynch added the action ‘could go on for a very, very long time’ as the union wants to ‘make the strike action as effective as possible’.

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