« Reply #6 on: Wednesday 24 April 13 14:00 BST (UK) »
Excellent marriage find!
The trick with the OPC search function is that you can't use wildcards, but you can use just the first few letters of a name. So, for instance, I searched for surname PEAR in this case, which would catch both Pearce and Pearse. I wasn't expecting a variation on Mary so I didn't search for MAR as the bride's given name.

The coverage page at the OPC site shows that it has baptisms for South Petherwin only 1656-1735 and 1875-1911, so that would omit the period when your Mary/ianne was born. FamilySearch doesn't have the images for that period either. You might contact the OPC for the parish to ask whether any info is available.
edit -- deleting bumph, see Kris's messages following and my later post.
HILL, HOARE, BOND, SIBLY, Cornwall (Devon); DENNIS, PAGE, WHITBREAD, Essex; BARNARD, CASTLE, PONTON, Wiltshire; SANKEY, HORNE, YOUNG, Kent; COWDELL, Bermondsey; COOPER, SMITH, FALLOWELL, WILLEY, Notts; CAMPION, CARTER, CRADDOCK, KENNY, Northants; LITTLER, CORNER, Leicestershire; RUSHLAND, Lincolnshire; MORRISON, Ireland; COLLINS, ?; ... MONCK?