I would say that there are sort-of demos of practically every single ska and reggae record issued in the UK but many are just ridiculously rare as they are plain white labels - pre releases - Blue Beat wise I've only had maybe three, but if I've had three that means there must be more. Island, I've had maybe four white labels. After that, the Trojan and Pama group issued white labels of every one of their 45's I would have thought, also many that didn't get an actual release. They sold at 7/6 each. As to availability, I know Island distributed records themselves for the first two or three years, by van.