I think it was recognised as the 2nd revival very early on, when the skiffle craze of about '54 onwards merged with folk, so that, e.g. at the clubs where Henry Morris's skiffle group played in the mid-50s, followed by the Nancy Whiskey club,[both at the Princess Louise] the 2nd half would include folksingers, like Henry [versatile] & Nancy herself [who employed at first a skiffle gp to start evening off as that was expected — but 2nd half, from about '55-'56 onwards, would include Ramblin Jack Elliot, Peggy Seeger, Bert Lloyd, Ewan MacColl — & anyone could see that a FOLK revival was underway. It was about then too that the Skiffle Cellar in Greek Street, run by Russ Quaye & Hylda Syms [who, bless them, gave me my 1st paid gig in 1956 — 10 shillings, well worthwhile in them'thar days] became the Folk Cellar with Steve Benbow's group, who were British folk not skiffle, the anchor group for the evening. ]That later became the Establishment Club {Lennie Bruce et al} & the original offices of Private Eye.]