STG
Sorry about the delay, computer went 'kaput', just sneaking some time on my other halfs'.
Reason I'm pretty sure she was illegitimate - 1881 census she is listed with her grandparents under the name Pocock. On a later census she is living with her newly married mother, but is listed as a visitor. Grandparents didn't have any other children of age to have had her.
When I looked up the registration district, pretty sure I saw Chesterfield for both. It probably changed and I missed the date of change. Sorry about that.
Once again thankyou all for your help
corndolly