I think the witness was spelt GANNICLI(E)FFT. He does appear on other marriages as a witness. Although christian name looks like Robert S, only birth I could find was for a Robert George Jury Ganniclifft, March Q 1851 in Newton Abbot. There is also a John Ganniclefft signing as a witness on some marriages.
Sally

Minister was Arthur Osborn Gibbes Alleyne who married them, was minister there from 1863
If you google the name of the church there is a link to encumbents.

If you can access the other weddings on the register it may be that the other person was a verger/parish clerk, brought in to witness when some could not read or write. signature might be better on other entries. am guessing first name Robert, and second name starts with S, and surname Ga......