After the conflict ended, he was part of the Tramp Trust Unlimited, formed by Maclean to propagandise and campaign for a minimum wage and a six-hour day, amongst other socialist policies.
McShane stated of the SRWP, that they "had some queer people that I didn’t like – they had never been to John’s economics classes, they knew nothing about socialism or revolutionary work.
He was shocked by some of the things he saw there, particularly the working conditions in a coal mine in the Donbas region, which he described as being like something from the previous century.
He met a young American journalist who had come to the USSR as a firm supporter, but had become disillusioned, as "people kept disappearing...and no-one asked any questions".
In the 1930s, he also fought to ensure that freedom of speech and assembly was allowed on Glasgow Green along with other socialist figures.