Naturalisation refers to the process of an immigrant to the UK being awarded British citizenship. An Act of 1335 first drew this distinction, requiring foreigners in the UK to pay double the rate of tax than natural-born citizens. Over time it became possible for aliens to improve their position through naturalisation. Until 1844, this could be done in two ways: either by a private Act of naturalisation, issued by Parliament; or by letters of denizen granted by the Crown. After 1844, naturalisation was granted by the Home Office.
Very few records of individual denization or naturalisation survive from before the first year of Henry VIII’s reign, 1509. The majority are held at The National Archives (TNA), with others at the Parliamentary Archives.
There are three main forms of record relating to citizenship: firstly duplicate copies of the certificates issued to successful applicants, Acts of Parliament, and letters patent; secondly, memorials or petitions presented by the applicant; and lastly, background papers on the applicant prepared by government departments. Where they now survive, the first two series are always filed together.
Petitions date from 1800 only. Before this date there are the Signet Office bills ordering the grant to be drawn up, docquet books (Series SO 3 and SO 4 on TNA's online catalogue Discovery), and duplicate docquet books, 1541-1761 (SP 38 and SP39).
A small number of original letters patent of denization (probably those unclaimed) survive for 1751-93 and 1830 (C 97) and 1804-43 (HO 4).
Grants of denization were enrolled in the Patent Rolls and Supplementary Patent Rolls (C 66 and C 67) from about 1400 until 1844, when responsibility passed to the Home Office. These are fully described in the printed calendars, which provide the only index for grants before 1509.
Online at Findmypast, you can search a collection of 12,959 naturalisation records from 1603 to 1700, taken from an index created by William Shaw in his Letters of Denization and Acts of Naturalization for England and Ireland.
Many early Acts of Naturalisation, from about 1400, were enrolled in the Parliament Rolls (C 65). The original private bills of naturalisation presented to Parliament, from 1497, are held at the Parliamentary Archives.
From August 1844 to August 1873, copies of certificates of naturalisation granted by the Secretary of State were enrolled in the Close Rolls (C54) – indexed by date (C 275). These include name of applicant, address, trade or occupation, place and date of birth, nationality, marital status, name of spouse (if applicable) and names and nationalities of parents.
TNA holds the duplicates of certificates and declarations, from 1870 to June 1980, granted by the Home Secretary under several Naturalisation Acts (HO 334). Findmypast also has a searchable index of nearly 100,000 naturalisation records from 1844 to 1990.
From June 1969, until December 1980, the Home Office did not maintain a set of duplicate naturalisation certificates issued to foreign nationals – index entries to these naturalisations are in series HO 409. HO 409 are nominal lists of individuals granted British nationality by naturalisation, 1908-1980. The lists provide basic information of name, original nationality, certificate number and number of the related Home Office file.
Both HO 334 and HO 409 are now searchable online on TNA’s Catalogue, together with naturalisations that were issued overseas, 1915-1982.
For the 19th and 20th centuries, TNA holds memorials (statements of facts) and petitions from those applying for naturalisation: 1802-71 (HO 1); 1872-8 (HO 45); 1879-1934 (HO 144). Not all documents are in the public domain: if closed, you can submit a Freedom of Information request.
