http://uk.youtube.com/watch?v=OOiCufYGH9I

They can also have the skimmers on the floor underneath the till, drop the card a quick swipe and then they have your details.

Hope that helps
Tim

P.S On a good note seems your bank is on the ball, I was impressed by Barclays too when they did this for me after I spent a large amount of money in one go on a transaction which was out of character. It's reassuring.