I read recently that bacteria, if present, are found on the surface of meat. As long as the surface of the meat is well cooked, it is fine to eat a steak rare. The problem is when the meat is minced and the bacteria is mixed to the centre of the burger. If the centre is not completely cooked, the bacteria will survive..
If i was in "classy" restaurant i would not have been concerned - however, in just a "normal" run of the mill pub for a quick lunch like muesli said, i personally wouldn't like the take the chance.