I think those Wylex plugs were "Council Housing" plugs in certain parts of the UK (Manchester comes to mind, could be wrong though), very interesting plug designs, kind of like an altered US style plug (yes, I know, they're nothing like them, but US plugs have two Flat pins and one Round or U shaped Ground pin), I've not seen them myself in person though, but the BS546 ones I have, and still use actually, cos being unfused, they're handy for centrally switched lighting or, as mentioned before, theatre lighting...
Anyway, that plug on the Goblin (I so wanted to put "Boglin" there, in reference to those rubber/latex puppet things!!) looks to be an old version BS1363 with the unsleeved pins, technically you're not supposed to commercially sell any electrical appliance fitted with them for "safety" reasons, as they can pose a shock hazard as they can be partially inserted in a socket and become live, but, I still use them, heck I polish the pins up and clean the plug up cos they're disappearing fast cos of the aforementioned "safety" reasons...
