At the mapping workshop on Wednesday 17th January 2018 one of the queries raised was to do with a brickmaker in 1911 at Kilsyth, Stirlingshire. Checking the Brickmakers Index there were two entries for sources that refer to Kilsyth. The first was Gartshore Brickworks at Kilsyth, Dunbartonshire. The second was for Gartshore Brickworks at Kiltsyth Stirlingshire. The Royal Commission on the Ancient and Historical Monuments of Scotland publication 'Brick Tile and Fireclay Industries in Scotland' has a diagram G3 distribution map of sites in Clackmannanshire, Lanarkshire, Renfrewshire and Stirlingshire. There is a small area between Stirlingshire and Lanarkshire that is unlabelled. This area is East Dunbartonshire. where this publication lists Gartshore Brickworks, Kilsyth as in the NGR location NS706743. It was thought there could have been two brickworks. However the 1956 OS map supplied from the National Library of Scotland web site [http://maps.nls.uk//view/91578896] of old maps shows a single brickworks on the north of the B8048 road and south of the railway spur that joins the Glasgow to Stirling main line at about Drumgrew Bridge. This was one of the colliery brickworks taken over by the NCB (National Coal Board) when they took over the mining collieries in 1946/47.
It just shows that places and parishes need to be checked. I good guide for England and Wales is Philimore's Atlas and Index. As an example in Bedfordshire Kensworth was previously in Hertfordshire and Swineshead was in Huntingdonshire.
Good luck with mapping your ancestors and I hope it helps you breakdown barriers.