London Underground warns tube strikes starting this Friday

Unless called off at the last minute, the RMT union will start a series of tube strikes on the London Underground in the run-up to Christmas, in a dispute over changes to driver duties for the Night Tube.
If the strikes go ahead, TfL is warning that they could mean a significantly reduced service on the affected lines all day with little or no service in places. Other tube, rail and bus services will therefore be busier to cope with displaced passengers.
The first of the strikes, affecting the C