Bit like the violin then.

No, nothing like the violin, which did find its way into folk music, where it found itself a fine home as the fiddle; the recorder, alas, did not.

People in England (and everywhere else) were playing and dancing to recorders, informally and recreationally, for centuries. Look at the iconography for a start. This instrument goes back to long before they had such concepts as "classical".

I think the instrument we're looking at here is the whistle flute, not the recorder which is a different beast altogether. Also most of that iconography is biased towards art music, or else a fanciful depiction of an unlikely folkish Arcadia in which aesthetic considerations outweigh those of ethnomusicology.

just means you're flash at playing your instrument, not that it has to be a concert stage performance. It can just as easily be done in the tavern yard.

The virtuosity I was referring to was that demanded of by the composers of the Baroque - Marcello, Telemann, Vivaldi etc., who were writing increasingly demanding scores for the instrument. See Here & elsewhere. I'm not talking about competent folkish musicianship, rather a technical virtuosity only possible in the various traditions of professional art music. It was for this that the recorder was developed.

Because you can cross-finger it and get sharps & flats, it can't be a folk instrument?   

I'm not saying it can't be, just that it isn't and never was. Latter day exceptions exist of course, such as celebrated Northumbrian Piper Neil Smith who plays as charmingly & as dexterously on his recorder as he does on his pipes, and Terry Wincott of the Amazing Blondel who gives us a flavour of how the recorder might have sounded had it ever been adopted as a folk instrument. Other examples abound, including our very own Walkaboutsverse who wields his plastic tenor in a manner that is most un-virtuosic, but hardly traditional, however so idiosyncratic such an approach might be (and however so philosophically loaded on the part of said practitioner). Otherwise, as a true traditional instrument of true traditional folk music, the recorder is nowhere to be found.

Because it's easier to blow notes out of, it can't be a folk instrument?

The fipple is not the issue here, a feature it has with other flutes and whistles, which are folk instruments, but which aren't recorders. My argument was that because it was easy to blow (unlike a clarinet, oboe or transverse flute) it was the ideal thing for the aristocratic dilettantes, just as it proved the ideal thing for school children before they graduated to a proper woodwind instrument.

Because it was eventually displaced by the transverse flute, this somehow invalidates its prior existence? Recorders were in use for hundreds of years, for a variety of purposes, before they died out. How does the eventual ascendancy of the German flute nullify that past history?

Things do die; in the case of the recorder it was killed off by the transverse flute. If it did have an autonomous existence as a folk instrument, it would have lived on, as other instruments did, but the recorder did not. The recorder was an instrument of art music from the medieval (at a stretch), through the Renaissance to the Baroque. It's 20th century revival by Dolmetsch (et al) was also as an instrument of art music, specifically for the recreation of sophisticated early music, not folk.

Yes - and where do you suppose the books got those tunes from???   From the folks playing them, dancing to them, singing them - some on fipple flutes. If that's not folk music, what is?

Again - fipple flutes are not recorders (though recorders are, of course, fipple flutes - an important distinction). The music might have come from folk traditions, as was the fashion, no doubt because along with the notion of faux-rusticity, such tunes were a lot less demanding for the aristocratic amateur dilettante than, say, a Marcello Sonata. As I said these 18th century recorder tutors were aimed at bourgeois hobbyists - hardly the traditional folk musicians whose rustic repertoires were greedily plundered out of long standing fashionably for same. Whatever the source of the tunes, the social context of the tune books is about as non-folk as you could wish to get, as, indeed, is the recorder.