I really don't know about that. The only think I can think of is the popularity of Percy's Reliques, that got people started collecting traditional songs (and trying to imitate them). As far as music goes, some of the traditional songs got printed with their tunes. Herd's 'Scots Songs', 1769, printed a version, if I remember correctly, of 4 verses of "Saw you my father", and there were 7 verses in the 1776 edition (no music for either edition). But between these two editions there was a 5 verse version printed as a single sheet song with music. So there was obviously considerable interest. Look at the folksongs that Robert Burns collected and gave in the 'Scots Musical Museum'. One is the incomparable "Tam Lin". Folksongs are rather rare in 18th century English songbooks, but a few Scots ones had some folksongs (The Charmer (4 editions), the Goldfinch, St. Cecelia and The Scots Nightingale are a few I've seen with what I would call folksongs) and a slightly better English source were the broadsides. The vast majority were not folksongs then, but a very few were. This interest carried over in Scotland through about the first half of the 19th century, with Motherwell, Buchan, Jameison, Maidment, Walter Scot, and others. Northumberland songs were collected by John Bell and helpers in the early 19th century (MSS edited by Dave Harker for the Surtees Society, 1985). But in England it was well into the 19th century that the Rev. Broadwood first collected English folksongs.