At least some of those aren’t monkeys. Monkeys have tails the one hanging on the curtain clearly has no tail. Nor do I see a tail attached to any of the others.
To me most look like chimpanzees. But the one on the curtain has a bare but which suggests baboon.
So to the 1,000 indeterminate (perhaps great) apes….?
UK is a strange country. I think it’s the only place gas, excuse me, petrol, mileage is figured in miles per liter.