Whoever made the GB bar plugs, also ( I think ) made the Milremo 'Star' plugs that came on a billion raleighs in the mid 1970's. Other than the writing on the plugs, all parts (shape, size, center screw, font, etc.) seem to be 100% identical.
http://www.sdbicyclegarage.com/
The Milremo Star plugs on all of my original bikes have crumbled away, and at least half of them have lost all of their writing. 1960's plastics don't seem to last for 40 years ...
Maybe someone who knew Ron Kitching / Milremo intimately could confirm that the same German supplier made both types of plugs ??
- Don Gillies
San Diego, CA, USA