Hi, Dave -- a wee bit busy here, but I had l had looked at my Scots dictionaries after I last posted and the consensus there seemed to be that the meaning of the questionable 'ev noo' would be even now / right now/ here and now. None of them used that spelling or transcription

At a funeral today I spoke to a fine North-east bothy ballad singer and he said that his preferred pronunciation would probably be "een noo" (meaning even now) -- though he also recognised that it would be understood in his area to say (with local accent, which would sound more like your 'ev noo') "of now".

Will try to get hold of the singer on your recording (Tom Spiers of The Gaugers), and will look up the various versions of the song in the wonderful Greig-Duncan Collection -- but I very much doubt that it would be assigned to music hall, though it certainly relates to the reign of Queen Victoria.