I understand that 'getting the wrong end of the stick' originated from the Romans use of a santary sponge on the end of a stick to wipe their behinds. The stick was kept in a bucket of water and re-used until it became too foul. Consequently, one took great care not to take hold of the wrong end of the stick.

Incidentally Tofctgyd, I grew up in Cirencester in Gloucestershire and we called the custom of knocking on doors and running away 'knock down ginger', so it was not just local to London.

Rog