Naturalisation certificates (The National Archives series HO 334 and HO 409)
You can search naturalisations from 1870 to 1980 online now that the naturalisation catalogue enhancement project has recently been completed. All those who successfully applied for British nationality in the United Kingdom and some who applied in British colonies overseas from 1870 to 1980 can now be searched for by name on The National Archives catalogue. Descriptions at item level (some 300,000) have been added to the catalogue in the Home Office record series HO 334, which are duplicate copies of the naturalisation certificates issued to the individuals concerned. This means you no longer have to come to The National Archives to consult the old Home Office printed indexes in series HO 409 to identify people who naturalised. As well as searching by name these records can also be searched by nationality and place of residence (county or town), which is recorded from 1878.
Ernst Freud’s naturalisation certificate BZ 1216 of 30 August 1939 (HO 334/228/1216)