I've travelled by ferry to both Northern and Southern Ireland several times and have only been searched once. This was on a work journey where it turned out my

I've travelled by ferry to both Northern and Southern Ireland several times and have only been searched once. This was on a work journey where it turned out my colleague had a criminal record. This was 10 - 12 years ago so perhaps things have changed since? I have been routinely searched before boarding a ferry to Spain as a foot passenger. AFAIAA, car passengers are not routinely searched, so I don't know what the logic is there?