Hello Christopher, not sure where you are based but there is a 40 or so page family history of the family of William Moorhouse m Mary Sefton 27 Dec 1773 at Pontefract Yorks. housed in the Canterbury Museum in New Zealand (where most of this family immigrated to in the 1850's).
I have a copy to hand......it extends to about 1932 and has extensive notes. Unfortunately that marriage (above) is as far back as it goes. I have also tried to trace this line back through the parish registers with little success. There is still one line of Moorhouses in New Zealand that can genuinely claim direct descent from this marriage although several others mistakenly do. Because of the fame that William Sefton Moorhouse generated in the 1880's as Superintendant of Canterbury many other lines began using the name Sefton here in New Zealand (including my own eg the husband of Faye Moorhouse who is kindly helping me through the Forum has Sefton as a second name). If there is anything I can help with on the New Zealand lines I would be more than glad to help right through to 1990. I would be interested in any steps back from William and Mary you can enlighten me on.