Steve, I adopted my Mudcat name because I am not really part of the folk world - just dipping my toe in from time to time. But since you have managed to get so close (Kent? South East London actually - but it was once Kent) I'm glad of the contact to compare notes. It may be better by PM to avoid gross thread drift.
I have a collection of some hundreds of theatre and music hall song sheets covering a wide range of dates, types and origins, but (and I hasten to say this, to avoid inviting random inquiries) it is totally unindexed.
I think you must have more Clifton's than I do. Sorting mine out from the heap may take some time (never had reason to do it until now). And, no, I've not seen HC's Death.
I am currently collecting (very slowly) song sheets of the early nineteenth century actors, Mr & Mrs Fitzwilliam, whose songs and style seem to me anticipate music hall by twenty years or more.
With regard to lithographs, I have always assumed that, because the published life of a comic song was quite short, there was never any need to renew the fronts but, when a song enjoyed continuing heavy sales,the stones would eventually show signs of wear. They were often crudely retouched (which is why we don't like buying them) but sometimes, I think, a completely new front was commissioned. ther was also, of course, some piracy.
I mustn't go on!