"The Invalid" wrote

Picked some apples from our tree yesterday and most of them had
maggots in. All seemed to have got in from the base of the apple in
the middle.

Will I need to put a tar band round the tree or are the eggs injected
in by flying bugs ?

Sounds like Codling Moth (small white "maggots" with brown heads?). Apple
Sawfly are similar but they attack the young fruit which fall early.
As for control, do a search, I'm sure the RHS site has info.

--
Regards
Bob H
17mls W. of London.UK