I think you may have solved the mystery somewhat!

See this document: https://historyofbath.org/images/BathHistory/Vol%2006%20-%2005.%20von%20Behr%20-%20The%...

It mentions Wilkins as a cloth manufacturer in Twerton. It also mentions a Francis 'Naish' who ran the Twerton Upper Mill up until 1824 (despite being declared bankrupt in the late 1818). It seems that in 1822, there was a "stoppage of all employment at the Manufactory of Mr Naish at Twerton" - so it seems my James Mathews was convicted of stealing from Wilkins while in the employ of Naish!

I will now go and search for any record of my James Mathews in Bath - just in case he is not the same James Mathews from Minchinhampton.