Rail unions are considering an offer that might avert a second major Tube strike over the thorny issue of the Night Tube.

The two sides met for talks at the conciliation service Acas on July 31 to try to break the row over plans to launch a new all-night service on selected lines, including the Jubilee line in the autumn.

Workers closed the Tube network completely in the first action and plan the same disruption during a fresh 24-hour walkout from the evening of August 5 through to August 6.

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The four unions – Aslef, Unite, RMT and TSSA – are unhappy at the pay and conditions over the night Tube which is set to be launched on September 12.

LU made a revised offer which will be discussed by union leaders on Monday, August 3, before the two sides resume talks at Acas. The new offer has not been increased in value but has been “re-shaped” in response to worries over work-life balance.

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Rail, Maritime and Transport union Mick Cash said: “Our London Underground reps will meet on Monday to look at the detail and we will take a response into the Acas talks following that meeting. RMT reiterates that [strike] action remains on.”

The distance between the unions’ and management position has already prompted the Mayor of London Boris Johnson to hint that the launch date might be delayed. On July 15 he said: “I can’t say exactly what date it is and I don’t particularly care but we’ll get it through this autumn.”