I wonder why Kings Bench? AFAIK that Court usually was for criminal cases. Many of the court records of that era went up in smoke with the Four Courts explosion in 1922. If (a big IF) the Nash case decision was of some note it might have been used as a precedent in subsequent cases so some later law books might have a reference to it. (Nash –v- Callaghan) but detail would be in broad strokes rather than fine detail. I would concentrate on contemporary newspapers – there was a fascination with law cases back then, much reporting of detail. Have you searched in ‘Saunder’s Newsletter’? Failing that I’d try a letter to the librarian in Kings Inns.