Qualtrough is possibly a married name and Robert Kerruish was Emily's second marriage. I have not fond a way of tracking back to the maiden names in such cases. You could try looking at the 1871 & 1881 census to ascertain whether there is any confirmation of Robert or Emily.
You could check the 1901 census, when available, or look for burial records for a possible Qualtrough in the years before 1886.