Conservative politicians are calling for a ban on tube strikes - arguing that they should be replaced with a compulsory mediation process.
A report, published by Conservative members of the Greater London Authority, claims that strikes have an "immense" impact on the UK economy - and should therefore be "outlawed".
Instead, an impartial judge would decide on a settlement.
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The inaugural service left London Liverpool Street for Shenfield, Essex, on the existing TfL Rail route on Thursday morning.
Councils believe that 600 high-rise blocks in England are wrapped in potentially flammable cladding, Downing Street announces.