Thanks for trying Wayne. I have her in all English censuses, from 1851 until 1911. I am only missing 1881. She and twin daughter Alberta cannot be found. Her other 2 girls are boarding at Holdenhurst so presumably she has gone away to work and maybe Alberta died, but no death certificate. Her husband is also a bit of a mystery and not certain. I am hoping to find where she is at this time as I hope it may shed further light on both her and her husband.
As I said, perhaps she may have been in France, Belgium or St Helena. I am not so confident of the available records there.