The baptism registers of St Mary, Islington show that Edward had a daughter Jane baptised in 1811 and a daughter Mary Ann baptised in 1815. In both cases the mother is shown as Ann.

Edward Frost married Ann Cannon at the beginning of 1817. Around that time Edward had a daughter Sarah who does not appear to have been baptised. From Census entries she could have been born any time from 1816 to 1821 (ignoring 1871 when someone's arithmetic seems to have gone 20 years awry!). I have assumed that her mother was Ann Cannon but have no evidence to support this. I have further assumed that this Ann was the mother of Jane and Mary Ann but again have no evidence to support this.

Ann disappears off the scene after all this and I haven't found a death/burial record or Census record. I suspect that Edward and Ann separated but being unable to remarry she may have assumed the surname of a new partner. There were a number of people called Ann Cannon and even with the information that one of the witnesses at her marriage was William Cannon (who could have been father or brother) I haven't found a likely baptism for her.