From Bristol Record Office:
"Bristol became a county by Charter of Edward III on 8 August 1373 and remained so until 1 April 1974. The records of Bristol are kept here at Bristol Record Office. Over the years there were various city boundary extensions; for example Bedminster which originally lay in Somerset came to be included within Bristol in 1835 and a similar extension took in Knowle and Totterdown in 1897. Therefore if you wanted, for example, a Register of Electors for Knowle for 1880 it would be at Somerset but for 1920 it would be at Bristol. Somerset Heritage Centre Brunel Way Langford Mead Norton Fitzwarren Taunton TA2 6SF
There is a similar situation on the Gloucestershire side of the city:
Westbury-on-Trym, for example, was included in Bristol by a boundary extension of 1904 so once again a Register of Electors for, say, 1900, would be at Gloucester Archives, Clarence Row, Alvin Street, Gloucester, Gloucs. GL1 3DW. Whereas a one for 1930 would be here at Bristol Record Office. Although this is all quite logical, I do understand how confusing it can seem to be when you are new to Family History! To determine which repository you need it is important to state the *type* of record, *date* and *place* that you want when you pose your question otherwise there is a chance of misunderstandings. For family history often church records need to be used; the churches had their own boundaries, Circuits for the Methodist church, Dioceses and Deaneries for the Church of England. The various Circuit records deposited here in Bristol Record Office include those for places in Somerset such as Cheddar or Weston-super-Mare. The Church of England boundaries are different and mean that we hold parish registers for churches both in Bristol itself and for an area to the north and east roughly bounded by Marshfield, Yate and Littleton on Severn. When indexers compile indexes of records for the benefit of other family historians it is entirely up to them how they arrange them. Bristol and Avon Family History Society divided its "1754-1837 Marriage Index" into two sections: North Somerset is one, Bristol and South Gloucestershire the other The LDS church includes Bristol for convenience under Gloucestershire in the IGI.
I hope this has done something to explain the difficulties you have been experiencing. As your research progresses I am sure you find that some of the problems resolve themselves but I have to add that after very many years of professional work in this field I still need to check up factual points of date and place regarding records on virtually a daily basis. It really is not a subject on which there can ever be a simple answer because of the way that local administrative and religious history has evolved over the years."
Stan