I went to Glasgow Science Park a few weeks ago. On an upper floor was a mirror the size of a shop window (Argos rather than Harrods). The idea was that you, if you were stupid enough, stood at one end of it and did that thing of raising an arm and leg so that you appeared, to anyone looking in the mirror, to be leaping in the air, spreadeagled. All the surrounding exhibits were populated (is that the right expression?), but not the big mirror. My grandaughter wanted to know why the mirror was there, so I tried to explain. Explaining was insufficient. Do you remember comedian Harry Hall on TV? He stood at the end of a shop window and did just that, raising an arm and a leg. The designers of the Science Park must have remembered it. And it was funny, sort of, as was my demo (solely for my granddaughter, you understand). Surrounding adults laughed, perhaps from embarassment. My granddaughter loved it, which hopefully justified the blushes.