There are clever spoofs of popular television programmes: Roman Mankychef examines the culinary peculiarities of our earliest invaders, whereas Guy Fawkes is the latest contestant on Who Wants to Blow Up Parliament?, opting to phone Robert Catesby when the going gets tough. “Not many Catholics in today” is Fawkes’s whip-sharp retort when one of his gags falls flat. I laughed but the primary school children around me looked on in benign bemusement. What got them going was the generous helping of poo and vomit gags that pepper the action. Toilet jokes, you understand, are never not funny. General Haig being called into the “war room” to account for the balls-up at the Somme to a furious Lord Sugar is, for the under-11s at any rate, a far more dubious proposition.