“Out to Lunch” by Bob Ellis and Clare Cummings

The basic plot is that a spectator signs a card which shows a boy climbing up the rope. However, when the spectator next looks at the card the boy has vanished, to be replaced by a sign saying OUT TO LUNCH. The cards are missing, but the instructions give a price of 3s 6d for purchasing additional cards. Although the manufacturer is not known, it is likely to be a UK firm given the mention of UK money. See N3116 for a Davenports Demon Series version of the same trick.