The National Union of Conservative and Unionist Associations was founded in 1867. The Midland Union was one of a number of area organisations (which also included the North Western and Southern Areas) which made up the National Union organisation. Between 1886 and 1930 the Midland Union covered most of the counties in the West and East Midlands. Separate provincial Areas were established in 1930, after which the name Midland Union continued to be used for the West Midlands Area only. However, by the 1950s the Midland Union only comprised of 58 constituencies in the West Midlands. As a result the provincial Area decided to adopt the name used for it by Conservative Central Office since the 1931- the West Midlands Area.
Reference: The Department of Special Collections and Western Manuscripts, Bodleian Library, Finding aid to the Conservative Party Archive (CPA) ((http://www.bodley.ox.ac.uk/dept/scwmss/cpa/)). Accessed April 2002.
From the guide to the The Letters Relating to the Midland Union of Conservative Associations, 1888-[1940s], (University of Birmingham Information Services, Special Collections Department)