Well apart from causing a mild disturbance of my wife - "what the hell is that !", I left the figure soaking in the Dettol overnight and this morning I cleaned him up with an old toothbrush under a running tap - and was duly impressed !
The cleaned figure - nice and shinny and a big hole in the the horse's withers (?) . I think the original figure was a hollow cast Life Guard but I'm going to make him into a mounted Prussian/German Officer .
The finished figure , holes filled up with 'green stuff' and a Irregular Miniatures Picklehaube head added, these figures are meant to be freestanding but I've added a base for stability . Will give him an undercoat when the filler is dry and post a photo when he is painted and varnished .