Thanks, Frances. That Knockold looks hopeful as a possible identifier.
Their other children bapt Ballaugh [IGI] were
MARGRET QUAYLE Christening: 12 DEC 1762 Ballaugh.
JANE QUAYLE Christening: 25 JAN 1767 Ballaugh.
If either of those bapts have Knockold, then it looks likely that their Philip was the death you found.

Unless the Margaret Quayle als Cowley 1783 decree has a son Philip. But there is always the chance that he was a later son therefore wrong age to be the one in Maughold.

Sue