John Clark was actually more than a member - he was a trustee of the Athol St Chapel - see www.manxnotebook.com/parishes/nc/cong.htm
I would also suggest looking at Manx Newspapers - these I think could be online - check if your public library allows access to the recently digitised papers (a jt effort between Manx Museum and British Library) - the marriage of a daughter of a leading douglas shopkeeper should be mentioned