Don - as much of the discussion above seems to say, I don't think the guitar ever really became part of the traditional folk arsenal in the UK!. Except for being taken up in the 50s and 60s, I don't think it was in widespread use.

I think there are reasons the guitar wouldn't make great inroads into traditional music. The early gut strung guitars would be very quiet instruments - before Segovia discovered Ramirez' guitars, which were loud enough to play in a small concert hall, the classical guitar was pretty much a salon instrument suitable only for very intimate recitals. It wouldn't have the volume to compete with eg flutes or violins or brass instruments. I think it needed the steel strung guitar to make it an instrument suitable for noisy environments. And the steel-strung guitar appeared relatively lately: Martin didn't build them before 1900 and the early ones were custom made, it wasn't until 1922 that it was in their standard catalogue. (There were other companies making flat-top guitars from late 19C). According to Tom and Mary Ann Evans The Guitar From Rock To Renaissance the less expensive Harmony and Stella guitars became popular with blues player in the 1920s/30s, and I think less expensive may be the key here (though the quality was meant to be good).

The same source gives Martin's output as 5,500 in the mid-1950s rising to 20,000 in the early 1970s. They claim "While the flat-top guitar became established in country and folk music during the 1920s and 1930s, its real growth in popularity did not come until after the Second World War. The folk boom of the late 1950s through 1960s, which was reinforced by the use of acoustic guitar by some rock and pop stars, had a dramatic effect on the guitar...During the 1960s the popularity of the acoustic flat-top became truly international".

My own opinion is that anything recognisable as an English folk guitar style came of out of the late 50s/early 60s folk revival. (I can still remember hearing Steve Benbow on the radio - early/mid-60s - and thinking it was the first time I'd heard the guitar played (as opposed to just simple chords) as an accompanying instrument to folk music; it impressed me deeply (and I did get to occasionally play in a band with him many years later)).

Mick