The Rail, Maritime and Transport (RMT) union will stage a demonstration against Southern Railway.
The union has reached agreements with a number of other train operators about the role of guards, but the row with Southern remains unresolved.
It’s caused misery for commuters across the Portsmouth region.
The union said rail workers from across the country will join the protest in London, outside the offices of Keolis, which owns part of Southern franchisee Govia.
RMT general secretary Mick Cash said the union had only ever faced ‘stubborn and point-blank refusal’ with Southern to enter ‘serious discussions’.
While a spokesman for Southern insisted industry safety bodies said drivers closing doors was ‘at least as safe’ as doors being closed by a conductor.