Workers at train firm Bombardier lobbied parliament last Wednesday.
Up to 1,500 workers face losing their jobs because the Tories refuse to give them the contract to build trains for Thameslink.
More than 50 staff from the company’s Derby plant were joined by 30 MPs for a rally.
Union rep Darren Barber said, “We have had amazing support from the public who feel we are being unfairly treated.”
RMT leader Bob Crow said the contract had been “a fit up from start to finish”.