I wondered if what Pepys heard was the 'Graeme' version. I've even looked at the possibility that the 'Reading' version was a parody of this and that 'scarlet' being the pun on 'Reading' was a further parody. All absolute conjecture and fancy. The 'Graeme' version does have more of the art song in it.

Jon,
No, the 'Graeme' version is in what I would call 'stage Scots', i.e., 'hooly, hooly' 'gin' for 'if' etc., the sort of stuff that abounds in Ramsay's works. However that very inventive fellow Peter Buchan managed to come up with a 41 stanza version in broad Doric. Needless to say, Child ignored it.