A quick Google of the search keywords "British Squirrels" turned up these results:
British Garden Birds - Squirrels
Squirrels
When a grey squirrel first arrived in the garden it was a moment of great joy and entertainment.
Soon, however, it became a nuisance as it ate everything in sight, including a plastic bird feeder! The seed feeders made from polycarbonate and galvanised steel have so far proven to be squirrel resistant.
There are baffles available for fitting to bird table poles, but so far our solution is working, which is to place grease on the bird table pole. The squirrel has tried a few times to climb up the pole, but each time it finished back down at the bottom and gave up trying.
If simple strategies like these do not work, there are many food additives, feeders, and contraptions available for purchase that claim to prevent squirrels eating bird food.
Working for Wildlife Caring for Squirrels
(excerpt) :
:There are two types of squirrels seen in the British Isles."
Perhaps they are like the 'camp followers' of the Crusades, and only arrived when the druggies started hiding their stuff in gardens? The mystery deepens.......