Free PassageBy Richard CarreñoBefore 9/11 my gateway of choice, Philadelphia International Airport, was as porous as the US-Mexican border is now. Conversely, I had always been impressed with security at London Heathrow, London Gatwick and Dublin, the three airports I most often use when traveling abroad.In fact, these airports had always been and remain, in reality, two airports in one. Following the European model, check-in areas are as 'malled' with fancy shops as departure-gate areas, except for the duty-free stores, of course. The result is that ticket-holders enter a cordon sanitaire when they move to the departure lounge.Secure? Surely, yes. At least, for departing.But how tight is security on arrival? I always thought that was tightly monitored, as well. The British and Irish aren't as squeamish about ethnic profiling as we Americans, and, as long as you stay out of lines with persons who you might trigger extended questioning, it's pretty much a safe bet that an entry for an American from Philly is swift and hassle free. 'What's the purpose of your trip?' 'How long will you be staying?' Bang! Your passport gets stamped.So you can imagine my surprise, then, when I actually discovered some new truths about security during some recent trips to the UK and Ireland. I sometimes fly to Dublin first, en route to London, and this was the case two summers ago. Security? How about this? I entered Ireland without passing through immigration and baggage inspection.As it happened, on that particular trip, I was traveling business class, and, as a result, I was among the first to alight. I just followed along -- OK, quite sheep-like -- my fellow-travelers. We turned there. We turned here. Before I knew it, I was in the airport's check-in area. Oops! Some of my companions just nonchalantly moved on -- into Ireland! I thought better of that. I retraced my steps, and managed to find the proper clearance officials.I don't suppose this cock-up happens often. But, as my experience shows, it happens.A few days later, I moved on to Britain. My flight took me to Gatwick. Because I was arriving from Ireland, there was no need, according to standard practice, for any passport control. I suppose the Brits think their security is covered by the Irish. But hold on! I could have been the same guy who had slipped into Ireland by error.