Hi Jean
James was certainly the son of James and Alice, however I'm not certain that he's the one you're chasing. I think he may have married Elizabeth Pearce on the 16 Apr 1778.
There is another James King baptised 29 July 1750 in Perranuthnoe who married Mary Pascoe on 27 Dec 1784 and they went on to have eleven children. She was his second wife, the first was Prudence Vincent who died 11 Oct 1784. This James parents were John King and Elizabeth Freethy and they married 10 Apr 1743.
Please note I'm an amateur and am quite willing to stand corrected.
It's all good fun and keeps me off the streets !!
All the best - keep in touch
Regards
David King
PS : Get a copy of Daisy Mays " St Hilary Baptisms " CD - It's a little goldmine and worth every penny !