The Horshaw Boggart was an event, featured in the Spook's Bestiary.
This event, which happened in the town of Horshaw (which is the town where Spook John Gregory grew up and lived), saw a boggart terrorise the village.
The boggart was a rank 1, and was bounded well by Tom Ward.
However, the boggart took with it just one victim - Gregory's preist brother, whom he describes as 'foolish', in an entry for his Bestiary.
A rigger, his mate and a stonemason helped the young apprentice to bind the boggart.
The boggart was seen to by Thomas Ward, the apprentice Spook to Gregory, at the time. The only reason that John Gregory did not see to the boggart himself was that he had fallen ill.