Hi Amanda, Whilst looking for information regarding William McKay " Whip String Maker" as part of some research I am undertaking for a friend, I happened upon your query.
William McKay is the maternal- 3xgreat-grandfather of my friend and your Maria is an elder sister to my friends 2x great-grandmother Elizabeth.
I believe that the William McKay listed as a " Clock-string maker" on 1881 Census at Openshaw is the correct William and he came back to Burnley later and died at Forrest Street and was buried at Burnley Cemetery on 7th March 1888, by the way a child of Maria's ( Massey Layfield ) is in the same grave!
Regards,
Glencliv972