Source Information UK, Naturalisation Certificates and Declarations, 1870-1916 [database on-line]. Provo, UT, USA: Operations, Inc., 2014.
Original data:

Duplicate Certificates of Naturalisation, Declarations of British Nationality, and Declarations of Alienage. Home Office: Immigration and Nationality Department, Series HO 334. The National Archives, Kew, England.

About UK, Naturalisation Certificates and Declarations, 1870-1916

With citizenship came the right to vote, hold civil or military office, and the ability to inherit land, but for immigrants in England, until 1844, naturalisation was a costly process. Beginning in 1844, the process no longer required an act of parliament and naturalisations could be granted through the Secretary of State for the Home Office

This collection includes naturalisation certificates, declarations of British nationality, and re-admissions to British nationality, as well as related correspondence, for the years 1870–1916.

Naturalisation certificates will typically list the name of the immigrant, residence, birthplace, age, parents’ names, occupation, and the names of any underage children.