John HOLYMAN was baptised at St Leonard's, Deal 16/12/1750, one of 4 children of John & Eleanor HOLYMAN. John, the father, was one of the children of John & Elizabeth HOLYMAN, all baptised at St Leonard's. Names and dates if you would like them.
John was, as you say, married to Mary FINNIS at St Leonards, Deal on 7/11/1775. John was living in the parish of St Mary's, Dover and Mary was a minor, marrying with the permission of her father William. Witnesses were Richard ROBERTS & Jane STRACHAN.
Regards
AJ