Where is Margaret in 1871
As I said earlier, I can't find Margaret, her parents or any of her siblings in the 1871 census.
I think you probably added it to your post after I had read it 
Going back to Patrick Keenan who do you have as his mother
Hi Rosie, I guess you are right, I edited the post after I spotted your question, my apologies.
I have Patrick Keenan's mother as Judith Crainah, I got that from the 1861 census, and the 1855 Baptism record of his brother Edward:
Name Edward Keenan
Gender Male
Baptism Date 08 Apr 1855
Baptism Place Pontop, Durham, England
Father Edwd. Keenan
Mother Judith Crainah
FHL Film Number 2082485
Household Members
Name Age
Judith Crainah
Edwd. Keenan
Edward Keenan
Other evidence from the GRO search facility is scant, but I believe on the balance of probability I have the correct family (famous last words of someone set for a fall).
Once again Rosie, thanks for your assistance, I really appreciate it.