At least I think that's who it is. At first, when I saw him in the garden very carefully sculpting a large round mass of earth, decorated with twigs, I thought the mystic moggie might have been having a bit of a close encounters moment of the feline kind. But later he had the tools out of the shed and was making installations from bits of cast iron and stainless steel that he'd found.
I see that the sculptor Paul Mount exploited the sensual qualities of hard metals, particularly cast iron, bronze and stainless steel, which he used freely to express a vision that ranged from the architectural to the figurative.
So it seems likely to me that it is indeed he who has invaded my kitty before he finds lasting peace.