My mom and I went to a pub for lunch the other day, and right where I parked the car was a bramble with some blackberries and I commented to my mom that we should pick them when we leave; to which she replied "oh but you need to be careful and not pick the ones lower down because of fox tapeworm". Apparently most foxes have it (well the German ones at least ) and it is transmittable to humans; so in Germany the rule of thumb is to only pick berries growing higher than your waist because a fox cannot wee that high.
Does the UK have a similar problem; do you know? Or do you just pick what you see?