So, I was just reminded - when I went to pull the post - that the 1984 Mercian Professional I acquired early this year and just fished out of storage has an odd-sized binder. The bike has what I think I've heard described as a 'Dutch' binder configuration on the seat lug, where the seatpost binder bolt screws into a threaded 'ear'.
The hex fitting is between a 5mm and 6mm size, and so I was wondering:
On a British bike such as this, of the mid-1980s, would that bolt likely be a 5.5mm hex fitting, or 7/32"?
The two measurements are very close, of course, but I wanted to see what I could find out...in the interest of precision.