A few days ago, I found that a plantpot containing a lovingly rescued plant (nearly killed last year, by vine weevil) had been half emptied, and with the soil and pieces of the plant scattered all around. The most likely culprit was the local neighbourhood squirrel.
Accordingly, I applied my usual squirrel deterrent, ie I re-filled the plantpot with sprigs of spiky holly leaves hidden buried in the compost.
The following morning there were some signs of digging, with one of the holly sprigs exposed - but nothing resembling the major excavations of the previous day. So I re-buried the holly, and levelled the compost.
Since then, there has been no repetition of the digging.
In the past, I've found such anti-squirrel measures very effective. If you have several plantpots, you don't need to bury holly in all of them. You only need to do one or two pots. I presume that once pricked, a squirrel treats then all nearly plantpots as no-go areas.