Hello Sue,
Thank you, again, for all this information and help.
I have had a look for a Will, but no luck yet - I will have another look for one.
But I suspect there won't be one as my William Corkill - Will CORKILL ballajorey buried Maughold Jan 28 1676/77 - would more likely have a Land Record mentioning he has died and naming his Son, William.
With, William the Son, having his Marriage Contract in 1677.
Some more searching to do in the Land Records.
Averil