I asked this in the thread about Steve Gardham's new work - deleted by a power-crazed mod (no idea who, probably the same one that's got randomly triggered by things I've posted before). So here goes again.

We sometimes know that a song existed long before we have any copy of its text. There may be a mention in a novel, someone may have been up in court for singing it offensively, or (particularly in Scotland) someone may have noted down its tune with a title that unambiguously identifies it. "Parcel of Rogues" and "The Braes of Balquhidder" are examples.

Has anybody tried to be systematic about that sort of evidence? It needs the same sort of crowd-sourced input as was used to compile the OED, so even wishing Steve another 50 years of productivity won't do it.