Hello Greentrad,
Saw you request for Shelvey/Thelvey some time ago but did nothing as I don't have the records of Sandwich.
Susan has been kind enough to eliminate Sandwich so I had a look at Deal. The name is mopre likely to be Shelvey, I think as it's a local name. Sadly, no Shelvey's matching the name and date in Deal, Walmer, Sholden or Northborne.
I did come across a Shelley. Spelling was atrocious in those days and people very often got written down with different names - it all depended what the Curate heard.
There was a whole family of Shelley's in Deal with a Mary baptised on 23/12/1798 to David & Lydia.
That's as near as I can get to being any help
Regards
AJ