The Nationalist Union Solidarity supported the nationwide demonstrations demanding that East Coast Main Line rail services remain in public ownership which took place today.
The protests coincided with the start of the Liberal Democrats spring conference in York.
Campaign groups called on Liberal Democrat MPs to keep the East Coast in public hands and oppose Tory plans for privatisation.
East Coast Main Line was taken into public ownership after its privateer owners proved incapable of operating the service.
Under public ownership passenger satisfaction rates for the service have soared and are among the highest for train operating firms across Europe.
The service has contributed around £800m to the Treasury, and since 2011 has received 35 industry awards.
Patrick Harrington, the General Secretary of Solidarity, said:
"I urge people to support these demonstrations as individuals. I worked for GNER which was a private railway running the East Coast Mainline for some years. I was convinced then as I am now that the railways need to be kept or brought back into public ownership and control".