When I'd looked for possible baptisms for Sarah there was one in 1810 which I'd discounted, because the birthdate of 16/11/1810 was too young to be her and it was also the wrong time of the year. That 1810 baptism had parents John and Mary, and for some reason (I can't remember why? did the baptism say he was from Pitsmoor??) I had it in my head that the John in Pitsmoor in 1841 was the one who was married to Mary.
Anyway, I got the digital image today (thank you Kevin for the tip!) of the 1844 death of John from Pitsmoor. The informant was a Mary Mallinson, presumably a wife, a daughter-in-law or an unmarried daughter. I think this points to the Pitsmoor guy as being the one who married Mary, because the one who married Martha only had two children, both girls, Hannah and Sarah.
Now, in 1841 Sarah had a William Mallinson (cutler, age rounded to 60) living with her. At first I did wonder if William was her father, but there are no baptisms to back that up. The baptism with parents John and Martha is a perfect fit birthday wise in terms of her age in the census and at time of death. That made me wonder if William was an uncle. William died in 1847 aged 69. I got the digital image for his death as well (praying that the informant might have been Sarah, and that a relationship would be given) but unfortunately the informant was the master of the Union workhouse, so no joy there.