You should never give up!
I posted this enquiry seven years ago and I think that I've just found Clara Elizabeth. A combination of a random Ancestry hint and FreeBMD led me to her. Her life wasn't straightforward!
In 1871 and 1881 she was living with the wonderfully named Horace Bolingbroke Reeve, a piano tuner, as his wife, in Norwich . I can't find a record of their marriage and it's likely that Horace's first wife didn't die until 1878.
In 1891 they are in Leyton in Essex, Horace is a musician and Clara is a machinist. In 1892 they had a son, William Horace, baptised Willie Horace. By this time Clara was 50. I can't find a record of any other children. Clara's birthplace of Bawburgh(misspelled but clear) in 1871 and 1891,makes it fairly certain it's her.
In 1894 Horace died and in 1896 Clara married Henry Hubbard, a widower with 3 children, in Stratford Essex. The marriage record in the Essex C of E marriage records give her name as Clara Elizabeth Reeve and her father's name as John Tann.
In 1911 the census places Clara and William in a household in Hackney with Henry, a "scavenger"(?) with the Borough Council, and his eldest, unmarried daughter and her 2 children. Again her birthplace is recorded as Bawburgh.
Henry died in 1912 in Poplar, and Clara in 1916, in Hackney. Her age is given as 67, whereas she was 74 but, again, I'm fairly certain it's her.
All comments, positive or negative, gratefully received!