Part firework safety warning, part mini horror film, there's something deliberately uncanny about this 70s Central Office of Information ad. The everyday scenes of football at the park and kids at the sweetshop are intercut with the uncanny - a mysterious child seen only from behind. The final shot of a group of such kids seen through a distorted lens could be from The Midwich Cuckoos. The perfect recipe for children's nightmares and sleepless nights for parents – it's certainly an unforgettable warning. (BFI).