He joined the Miners' Federation of Great Britain (MFGB), and through this role, helped organise a major demonstration in London in 1925, where he heard Herbert Smith and A. J. Cook speak, becoming a supporter of the two miners' leaders.
[4] Following the UK general strike, Machen struggled to find work, but eventually gained employment at a colliery in Thorne in Yorkshire.
[4] There, he joined the Miners' Federation of Great Britain (MFGB), and rapidly rose through its ranks, first within his local union branch,[3] then in 1945 becoming the regional Compensation Agent.
[5] Machen first stood for the post of President of the National Union of Mineworkers (successor to the MFGB) in 1945, coming second to Will Lawther.
[4] He stood again in January 1960, but on 2 March died suddenly in hospital in Leeds, aged 59.