In Lancashire my Granny still called me for fun, Michael o'Bessie's (my mum). It had been a common way of distinguishing people with similar names or to show parentage.
re Carolan's tunes, I often wondered about how they were passed on. I think it was the tremendous memory within the old bardic tradition which was part of the education and training.It was still alive as the Gaelic aristocarcy was fading.
I read a tale of how Carolan hid and learned a piece by a visiting musician (maybe an Italian Baroque maestro)and then played it before him claiming it as his own composition. Quite a joker!
Most traditional musicians I know have hundreds of tunes by ear and memory and most don't seem to be dot or ABC readers. Also the local repertores were probably smaller than today and committed to memory by long aquaintance.
he seemed quite happy to play for the toofs and with the ordinary people for ancing as well as listening and he certainly liked a jar.