The assembly alibi ... that really is a great alibi for a guilty person. I have been to two recently, at the first I recall speaking to one other school parents because I took relatives with me, at the second I spoke to one other school mum, saw another rellie and think maybe another acquaintance was there. Months later I won't remember much past I went with my rellies to one. Lots of people taking videos and photos so I guess they could identify some people by the backs of their heads. But given how many people are there and how few could vouch for me and how few I could vouch for, with the existing relationships as motivation to lie or to let confusion be trumped by loyalty, if you were guilty it's a good one to run with as you at least have something. Not so great for an innocent person though.