I'm not sure about this - you haven't given Marianne's marriage date so we don't know whether she is still single or not? Three members of this family match exactly for date, obviously the youngest would have been born since the last census, and it makes me think it's them all having moved to London, in the absence of finding any other family, but the change in occupation seems a little strange .....
16 Queens ?? Kentish Town, St Pancras, London
William H Pavey Head Mar 54 Cabinet Maker Devon Plymouth
Charles Son Unm 18 Joiner in Wood " "
Fanny F daur 12 Scholar " "
Harry R? Son 8 " " "
RG9/ 122; Folio: 40; Page: 11
6 Raneleigh Road, St Mary Paddington, Middlesex
Frederick Pavey Head M 27 Carpenter Devon Plymouth
Eliza Wife M 26 Middlesex Islington
Alice daur 1 Middlesex Bayswater
RG9/ 6; Folio: 51; Page: 45
21 St Paul's Street, Cheltenham, Gloucester
Jemima Constable Lodger Unm 39 Tailoress Blumsdon Wilts
/
William H Pavey Lodger Unm 27 Tailor's Foreman Plymouth Devon
/
Thomas Fitzgerald Lodger Wid 42 Tailor Bath Somerset
/
Charles Joy Head M 36 Wollen Draper's Assistant Schlade Gloucester
Sarah Wife 40 Cheltenham
Albert Son 5 Scholar "
Florence daur 3 " "
RG9/1799; Folio: 22; Page: 37
I can also find this Charles and Harry, both separately living in London in the 1871 census but would like confirmation from you that this might be the right family before going into more detail. What happened to Marianne? when did she marry and to who?
Could this be your Marianne??
Marianne/Maryanne Pavey married December qtr 1858 Pancras 1b 53 to either William Francis, Reuben William Harper or Reuben Turner.
I would seriously consider that this family moved from Devon to London, there are too many of them floating about there for it not to be them. Can't say where Elizabeth is though?
I have to go out now, if I get time when I come back later I'll take another look to see if I can find Marianne with one of those surnames, she should stand out from the crowd if she stayed in Pancras born in Devon, meantime I'd appreciate some confirmation whether you think these are yours and also if you know for sure what her married name is.