Theoretically the signals square. They seem to be going out of fashion. Maybe AG radio?
What if it's an airfield like (for example) Bembridge where it is not actually "closed" but is unmanned on certain days, so there is no signals square. Circuits only allowed on one side of the aerodrome so circuit direction reverses according to the wind direction which you gauge from the windsock, and make blind calls. If it's nill wind, and you're non radio, you could be caught out by someone who happened to have chosen the opposing runway.
OP, might the cub you saw have been non-radio and simply joined the circuit, happening to choose the opposing runway to you for whatever reason (you mentioned it was nill wind), and then decided to abort the landing? Maybe it wasn't obvious which runway was in use?