Strange you should come up with that interesting fact, Ivo, as when I wrote my reply I wondered whether it could be a modern Continental version of an old design, like the modern French version of the Davidson dome flower block.
Anne, your insulator seems to be a version of the Dawkins insulator, made by Percival, Yates & Vickers for Thomas Dawkins of 4 Little Warner Street, Clerkenwell, London EC, probably piano makers / dealers, regd. 8 July 1859. It later appears with a concentric ring base, which might be by Sowerby, possibly early to mid C20, and then with a cross-hatched base like yours, unmarked on the upper surface.
I've had all three of these lined up together, and, apart from the bases, they are indistinguishable.
Bernard C.
