Have managed to do some more research, including, but not exclusively, the old IGI fiches and Family Search. Started with wiondering if there was a relationship with Ann and John the Vicar of Hatherleigh (1701-1721) so did a google search which opened up a "magic door" by finding quite a detailed WikiTree site which shows John was a first child of Oliver and Elizabeth, so John was the eldest brother of Ann(e). Have gone through the details and they all "stand up" to comparison with the rest of my research, apart from 2 items. It says Oliver and Elizabeth (who they say was Yeo) were married at Meeth, whereas the WikiTree details say Exeter. Also, as you can click on the other members of the family, it says that Ann and Digory (they don't know his parents) only had 1 child - so they haven't looked for the rest! so thanks for where your information has led me.
David