Well there is no such thing as being naturalised English (it is British or nothing). but presumably Anne Sunnucks meant British citizen.John Upham wrote: ↑Sun Jan 24, 2021 12:17 pm...From The Encyclopaedia of Chess by Anne Sunnucks :
"Meanwhile, Zukertort had decided to make England his permanent home and became a naturalised Englishman in l878."
I assume Anne did not make-up the 1878 date.
Is being a "naturalised Englishman" the same as being a "British citizen"?
But she was wrong and any source she used was wrong, I am pretty sure. So if Jimmy Adams looked and did not find, he came to the same conclusion as me but I haven''t discussed this with him.
If you search the National Archives http://discovery.nationalarchives.gov.uk/ you will not find a naturalisation record for Zukertort.
You can find the reference online for the naturalisation papers for Lowenthal, John (1866) and Gunsberg, Isidor (1908) which I found and read in Kew when researching my "Eminent Victorian Chess Players."
When Lowenthal applied there was a 15-year residence rule so he applied and obtained citizenship in the earliest year he was eligible, having come to Britain in 1851.
In 1870 there was a new Act reducing the minimum residence to 5 years so it is possible that Zukertort (who came to Britain in the summer of 1872) could have applied in 1878 and failed to get it, which could account for there being no file in Kew.
Maybe he pretended he was naturalised, just like he pretended he was a doctor?>