There was also a Cooper 316 - a baby sister to the 352 and 416, as well as a 502, a 50' version which is where the concept and the lines come together to make a rather handsome boat. Not many 50s were builts, AFAIK
I think US yachts only built the "35" and "42".
Here's a Discovery 42 (they were produced as both aft cockpit and pilothouse versions)
As you can see this is a DIFFERENT boat than the Cooper/US line and is designed by Peter Hadfield, not Stan Huntingford. Link: YachtWorld.com Boats and Yachts for Sale
Compare to the Cooper 416:
Here's an example of the 502 (not its best angle.....)