In reply to Jim Walton:
Agreed, it was huge, almost biblical.
I had the dubious privilege of arriving at said belay ledge moments after the offender departed....leaving what can only be described as a behemoth, steaming turd in HER wake, last Friday mid-morning.
Given the size of the monster, I was more than a little bit surprised to observe that it's owner was a rather sheepish looking 20-something female on a PYB rock climbing course. She was the last climber in a group of 3 who were climbing in series, the leader was a PYB guide. She left the beast just before departing the ledge - probably unobserved by the two climbers above her.
She wasn't exactly a big 'un..how she managed to squeeze out a number 2 the size of a cannon ball is beyond me.
She'd probably make a very successful drugs mule.