Crank Help!

Those are Williams AB77 cranks - the finest British cranks available in the 1960s:

http://www.classiclightweights.co.uk/components/williams_identification.html

You often see them installed on Moulton "S Speed" factory specials.

The bolt circle is the same as the TA 5vis/Stronglight 50.4mm, so you can fit the adapter and ring to TA Pro 5vis or Stronglight 49D cranks or a host of clones and copies. The ring is probably a 151mm bcd, which was the old track standard before 144mm took over.

In terms of splined crank history, Williams weren't the first: Gnutti were doing it in the fifties.

have to admit that's impressive.