I think he made 4 or 5 of them up until the early 50's. Pretty much completely hand made. To say it was made by a 19 year old in a shed is a little disingenuous though, he did have a mill and a lathe. And obviously some mighty skills, and probably a good teacher!
An old acquaintance of mine who grew up in the 60's in the UK reckons the the term, when applied to the form of customised bike and its use by the original hard core but fringe group (of which he was one - a rocker in the 59 club), although originally intended as an insult (by what riders considered to be the ignorant mainstream anyway) was embraced and worn as a badge of honour by the true believers but became somewhat maligned later when all the wonnabe's (posers more than riders) joined in.
As an aside, he continued to live the dream (still riding his first Triton and later Bol 'dor Honda) up until his death a couple of years ago.
There is surprisingly little mention of cafe racers in my collection of UK bike mags from the early to mid 60s. Plenty of articles about rockers and the 59 club etc though, most of which would generate a flurry of indignant letters from "ton up boys" who considered rockers to be poseurs of the highest order. From what I can gather, cafe racers were bikes that looked like racing bikes of the day, but couldn't pull a ton. Mind you, most bikes back then couldn't pull the ton, but to the serious ton up boy having a bike that was all cock and no balls was an even greater sin than riding a slug!