Robert,
We have Badgers, and Wild Boar that attack hives fairly frequently.
Seeing that you are in Birmingham - I suggest that it is the latter that
is causing the problem. Anywhere else in England I would have put it
down to big mice - apart from S.W England where there are vicious sheep
that have developed a taste for honey. Don't collect supers during the
night as they tend to go around in groups.
If the marks on the hives are round shaped then get  in contact directly
with MAFF as you might have a case of acute Woodpecker holes.

Hope this helps
Yours
Peter