Info taken from book 'Biker' by Bill Osgerby. I have not seen it, would like to do so, but not for its currently going price!
Alternatively entitled 'The Damned', it was produced in 1961 but not released until 1963 for some reason. Probably the first movie to feature British bikers, it was an unusual science fiction tale and features Oliver Reed in his first major role, this time as 'King', the cold blooded leader of a pack of motorcycle thugs - but Reed appears as the only one of his gang not wearing leathers.
Who knows how good the film really was? It's clearly not currently released, but we can only hope......