"Hecky THUMP!" I thought.

Sounds like an Orange day parade ...

except

A) We're not in ireland.
B) I'm sure it's out of season.

There's a drama-workshop type thingy, not all that far from our patch, and they're often given to loud and disturbing noises, clearly audible above the strains of my little wind-up radio.

Toddled off to the fence at the bottom of the garden for a peep, since it didn't have the muffled toned indicating it was escaping through the brickwork.

Lo and behold, strange "gannin's on" in the school field.
Too late to add, as we were en-route for the Guinness sans camera when we beheld an instant wall, swarming with sprogs trying their hands at "rock" climbing, out of sight from here beyond the school.