According the the union, Unite, London Underground faces the prospect of a complete shut down this Bank Holiday weekend as workers, who control the power to run the trains, prepare to strike.
Unite regional officer Hugh Roberts said:
"There is a real possibility that the underground could close down over the bank holiday weekend. Unite is working very hard to achieve a fair settlement for our members - and to avoid the industrial action. The ball is very much in the management's court."
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A lamp in the tower which houses Big Ben is to be switched off for the first time in more than 70 years.
Sir Bruce entertained audiences for more than seven decades.
Work in the tower will also pause over the bank holiday weekend.