Glamorgan Marriages, 1837-1922 collection has been posted on FamilySearch.org at https://www.familysearch.org/search/collection/show#uri=http://hr-search-api:8080/searchapi/search/collection/1392564
I’ve found 31 COMPTON entries, which are not part of my One Name Study and 1 CUMPSTONE entry. So if there is anyone out there researching COMPTON take a look at this link.
So what about the entry I am interested in? It is a marriage entry for Ernest Edward Cumpstone born 1874. He was married 5th June 1897 aged 23 years at Merthyr Tydfil Glamorgan, Wales. His father was William CUMPSTONE and he married Elizabeth Ballard daughter of William Ballard. Both were single.