Due to the bread always dropping from a successful pickpocket, bring some food to start, then you can stay in the Watchtower pickpocketing and eating the bread without having to refill at the bank in Yanille. Trap the watchmen in the north or north-west of the room along the beds. Allow them to walk on the 2 tiles between the beds to avoid them despawning, which happens if they stand still for 5 minutes.
With a constant source of food, the ability to solo trap them and the higher number of them in a small area, this is more idle than a Knight of Ardougne in East Ardougne, though it does have a higher failure rate.
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