Can you explain why you think the 1841 cesnus is subject to copyright. see below, specifically the last paragragh.
www(dot)hmso(dot)gov(dot)uk/g(hyphen)note3(dot)htm
1. In the Government White Paper, The Future Management of Crown Copyright, it was announced that copyright would be waived for certain types of material which are Crown copyright protected. One of the categories of material which is covered by waiver is unpublished Crown copyright protected public records. "
www(dot)hmso(dot)gov(dot)uk/document/cpy(hyphen)05(dot)h tm
Provision of Crown copyright public records
PRO document 15 5.5 page 6 0f 19
5.5 The Government announced in the 1999 White Paper The Future Management of Crown copyright (Cm4300) that Crown copyright will in future be waived in most public records held in the Public Record Office, the National Archives of Scotland, the Public Record office of Northern Ireland, places of deposit of public records appointed under the Public Records Act 1958 and any Welsh national archive that may be established by the National Assembly for Wales. 5.5.1 Crown copyright will continue to subsist in public records, but will not be enforced in public records that are available to the public and that were unpublished, or contain material that was unpublished, at the time of when they were deposited. Users are free to copy, index, transcribe, publish and broadcast such Crown copyright material without formal permission, payment of a copyright fee or acknowledgement of copyright. The appropriate record office's custody of the original documents must nevertheless still be acknowledged, and the archived document reference given.
www(dot)pro(dot)gov(dot)uk/about/copyright(dot)ht m
www(dot)pro(dot)gov(dot)uk/about/co p yright/copyright(dot)pdf
The 2nd one is an acrobat file. If you can view it, scroll down to 7.1.1. If you can't, here is the relevant passage:
Crown copyright will continue to subsist in public records, but will not be enforced in public records that are available to the public and that were unpublished, or contain material that was unpublished, at the time when they were deposited. Examples of such material are census returns, records of services.....Users are free to copy, index, transcribe, publish and broadcast such Crown copyright material without formal permission, payment of copyright fee or acknowledgement of copyright. The appropriate record office's custody of the original document must nevertheless still be acknowledged, and the archival document reference given. Crown copyright material among non-public records in the PRO will be treated in the same way.