I agree Jos. I'm usually smiling (although my pupils used to tell me I'd put on my 'scary face' when displeased, and they found it very effective!)

The prisoners I visited told me they had ways of distorting the 'mug shots' which the Police took of them when in Custody. They'd put their tongue in front of their bottom teeth, hang their chin down and generally gurn for the camera, with the result that their identity photos looked nothing like them at all.

With modern technology though, a single fingerprint on the little device the Police carry and their identity is immediately verified.