Ah, Chamossaire, loco of my boyhood dreams.
Along with Woodcock, whose corridor tender we ventured through whilst it was on shed at Doncaster, and Hal O' the Wynd, sitting waiting entry to the works, but could be viewed nicely by running along "Dog **** alley" and viewing through the tiny gaps in the fence.
Unfortunately, running along there whilst NOT looking where one was putting one's feet aptly revealed why spotters chose to call it that.