Spotted...

was that @jammy 's at some point?

I can't imagine that more than two or three bikes of that size were ever built by Bob Jackson, so they might well appreciate it if you sent that photo to them.

It's either a frame that's old enough to have been built when the idea was that very little seatpost should show, or it's no longer with its original owner and the new owner has slammed the saddle. :)

@ObiWomKenobi somebody actually built it!

Can only imagine how much of a noodle this is. My old 66cm 531c frame was all over the shop so this thing must be ridiculously flexy.