I found an intriguing mention of my Mansel relation in a book called Welsh Murders Volume 1: 1770-1918. Written by Peter Fuller and Brian Knapp, published 1986.
There is a chapter called Glanareth – The Glanareth Conspiracy which took place between 1769/1770. A murder took place in Glanareth, Bethlehem , Carmarthenshire.
The story mentions Sir William Mansel my 4x great grandfather. I want to find a copy of the book, or this story, so I can see more. I know that it mentions Sir William as a gentleman/member of the ‘Blue Coat Hunt’.
For extracts from a contemporary pamphlet account of the trial see this blog post: http://sharonhoward.org/waleslaw/glanareth.htm
