Back in about 1982 or 83, I bought a Simpson (not a butterscotch) with a knot very like this from their shop in London. It was occupying pride of place in their window display, and I drooled every time I walked past on my way to/from work, and at the time I was relatively flush with cash. I can't remember the exact figure, but I think it was north of £300 even then. Who knows what it would cost now, if it were even available. It lasted with daily use for over 30 years, but now it only has a little more hair than I do. Somewhere I've still got it, but it might be an awkward re-knot: the socket is 31mm diameter, a little tight for a 30mm knot, but a little loose for a 28mm.