I travel out of Heathrow regularly, and on many occasions I have simply just walked around the shoe scanner machine, essentially making the screening optional.

I was running late for a flight a few months ago, and to my surprise the security official just waved me around the machine, which had a fairly large line of people waiting. Since then, whenever I travel out of Heathrow, I just walk around the machine, and I have not been challenged once, regardless of whether I'm suited and booted or wearing jeans and a tee.

This just shows how absurd airport security is nowadays. Letting just one person through unscreened makes the entire screening process close to futile.