« Reply #2 on: Tuesday 09 January 18 14:04 GMT (UK) »
Firstly you won't get a certificate because the marriage is before July 1837 when civil registration started, so all you will get is the original parish register image with less information than post 1837.
I suspect the marriage could well be at Kensington St Mary Abbots because Ancestry only has images to 1819 but the parish registers start in 1539 according to Familysearch Wiki. If you want to browse those parish which Ancestry has images for go to -
https://search.ancestry.co.uk/search/db.aspx?dbid=1623 - select Kensington and Chelsea from the Borough under "Browse this collection" on the right side of the page and look through the parishes available. Selecting the parish name will tell you the years that Ancestry has.
(KENT) Lingwell, Rayment (BUCKS) Read, Hutchins (SRY) Costin, Westbrook (DOR) Gibbs, Goreing (DUR) Green (ESX) Rudland, Malden, Rouse, Boosey (FIFE) Foulis, Russell (NFK) Johnson, Farthing, Purdy, Barsham (GLOS) Collett, Morris, Freebury, May, Kirkman (HERTS) Winchester, Linford (NORTHANTS) Bird, Brimley, Chater, Wilford, Read, Chapman, Jeys, Marston, Lumley (WILTS) Arden, Whatley, Batson, Gleed, Greenhill (SOM) Coombs, Watkins (RUT) Stafford (BERKS) Sansom, Angel, Young, Stratton, Weeks, Day