Hundreds of thousands of rail passengers have faced delays and cancellations as South Western Railway workers begin a 27-day strike.
Workers will walk out for 27 days between December 2 and New Year's Day, threatening travel chaos for commuters and Christmas shoppers.
Workers on South Western Railway are to stage two fresh strikes, including on New Year's Eve, in the bitter dispute over guards on trains.
A South Western Railway service partially derailed in the Wimbledon area during rush hour, and disruption is expected to last for the day
The RMT made the announcement as part of a dispute over the role of guards on trains