Arrived at the Tunnel French end at about 12.15 local time and took Archie to the pet passport centre. Didn't think to check under MH not that it would've made any difference and proceeded to ticket collection passports etc. Full inspection underneath by armed copper and then we parked up and had lunch. We got called for the 13.50 train and drove until the very last barrier before descending down the ramp. The fellow at the barrier didn't seem like a security type, more just to check out ticket but he bent down and looked under MH. When he started shouting "Allez, allez" I didn't think for one moment it was for the armed copper with the biggest Rottweiler in creation. I looked into the nearside wing mirror to see a young guy drop from underneath the MH whereupon he sat crosslegged with hands on head, last thing I saw was this copper and dog descending on him. The only place he must have been able to get access was in the so-called secure area after check-in.