Hi Sammybill,
looking for Mary Ellen Brown born 1855/7
I see that she was just called Ellen on the 1861 census and that her mother Ellen was a Travelling Pedlar - it's possible that her birth may not have been registered ~ Durhamrecordsonline has a baptism for an Ellen Brown b. 1856 bapt 1857 in Seaham, but her parents were Michael and Mary Brown, and they don't have one for a Mary Ellen.
She's also just called Ellen on the 1871 census - I was wondering where in Yorkshire Rebecca was born, couldn't make the place out on 1861 census, but it's clear here - Bacup
Lancashire, and I can't see her birth registration either!
1871 RG10/4883 Folio 70 Page 33
6 Mass Yard, Darlington, Co. Durham
Ellen Brown head wid 47 Hawker Ireland
Rebecca " dau s 18 General Servant Bacup, Lancs
Ellen " " s 16 Sempstress Seaham Harbour Durham
Barbara