These refer to the Hart's annual army list, militia list and yeoman cavalry lists which were originally compiled by Lieutenant General Henry George Hart (1808-1878) and was published annually between 1840 and 1915 with the Indian Army appearing from 1862. It certainly includes information about the Somerset Militia. Since receiving them I have discovered that fuller lists can be accessed from the National Library of Scotland which also include information about the RAF and Naval personnel for WW2. British Military lists - National Library of Scotland (nls.uk)