Claim: The union that had the most members in 1907 was Kirkintilloch and Twechar Miners' Association, which was founded in 1893, and the second union with the most members was Scottish Shale Miners and Manual Workers' Union Association, which was founded in 1886.
Evidence: Lanarkshire Miners' Federation 34,000 Kirkintilloch and Twechar Miners' Association Scottish Shale Miners and Manual Workers' Union