Yep, you've nailed it.
Golden Wonder were the premium brand when I was a kit.
Cheese and onion is still green in my head - because of the onion, not the cheese really!
When I was young, I always thought that Smiths was the premium brand and they were ... until 1965 (when GW caught them up)
Our favourite brand was Chipmunk - which seems to have vanished pretty early.
Yet, all of them (Smiths, GW, Chipmunk, Seabrooks) had blue for S&V and all, bar Seabrooks, had green for C&O. So, Walker wasn't just acting agains GW but the entire crisp industry