[Osem]

If the EU's external borders are based in places like Greece as a direct result of Schengen, it does indirectly affect us because it enables illegal migrants to penetrate far deeper into Europe than they otherwise would and wind up in places like Calais which is a lot closer to home than Greece. Instead of facing numerous border checks and the risk of being caught and stopped at each, it's go direct to France or Belgium or Holland. Of course if our borders were really secure it wouldn't matter so much* but they're not so it does.

Schengen also facilitates criminality within the EU as was recently demonstrated after the Paris shootings. Again, it just brings the risk factors to our nearest neighbours rather than keeping more of them on the perimeter of Europe.

*Legality and illegality have come to be irrelevant so far as migration is concerned. Plenty of illegal immigrants wind up being granted asylum in the UK for one reason or another. The guy who walked through the Channel Tunnel recently is one such. So called security isn't much use if people who breach it are rewarded instead of punished.