We had screens on wheels in latter years at, last few years at school and er  he used to go down to the tea room for a cup of tea half way down the stairs, the teachers' room and perhaps go toilet as well, and er  the one at the back was a foot out from the screen and every now and then he'd have a look to see if he was coming and er we, what had  had a big case with birds in and the lads who were doing it looked in this, saw the reflection and shh he's coming.