There were (at least) two Robert Riders in the area. The other one was born in Swannington c 1767 and signed up for the army, but was quickly discovered to be unfit and discharged:
https://search.findmypast.co.uk/reco...21%2F121045495
He, however could not write, whereas my man (and the testator of the will) was literate.
The will is odd, with Mary Seely, wife of Robert Seely, shoemaker of London and Mary Knights, wife of John Knights being the beneficiaries, but neither apparently being close relations.
I am beginning to wonder whether the marriage was annulled.