They can get through a gap of 1-2mm (about 1/32 - 1/16 inches) through cracks round door frames, along the holes for water pipes, in tiny cracks between bricks or concrete.
They have an amazing sense of smell and are especially fond of cat food or that tiny bit of lettuce that fell underneath the fridge.
Much of Britain, certainly.
They can get through a gap of 1-2mm (about 1/32 - 1/16 inches) through cracks round door frames, along the holes for water pipes, in tiny cracks between bricks or concrete.
They have an amazing sense of smell and are especially fond of cat food or that tiny bit of lettuce that fell underneath the fridge.