British is no ethnicity, just nationality. You can be turk, greek, jewish ethnicity and citizen of United Kingdom (= british) at the same time. Issigonis was british as his father was british citizen as well.
Bingo and you didn't even have to read the link.
Alec Issigonis - Wikipedia
Alec Issigonis was born 18 November 1906, into the
Greek cosmopolitan community of the Ottoman port
Smyrna (now İzmir, Turkey) in
Asia Minor. The son of Greek and German parents, he inherited British citizenship via his father and developed very "English" attitudes.
[6] His grandfather Demosthenis migrated to Smyrna from
Paros in Greece in the 1830s and through the work he did for the British-built
Smyrna-Aydın Railway[7] managed to acquire British nationality. Demosthenis's son (Alec's father) Constantine Issigonis (
Greek: Κωνσταντίνος Ισηγόνης), was born, with British nationality, in
Smyrna in 1872. Constantine studied in England. Alec's mother, Hulda Prokopp, could trace her origins back to
Württemberg (now part of Germany). It was through his mother's kinships that Issigonis was a
first cousin once removed to
BMW (and more briefly
Volkswagen) director
Bernd Pischetsrieder.
[8]
Because Alec and his parents were British subjects, they were evacuated to Malta by
British Royal Marines in September 1922, ahead of the
Great Fire of Smyrna and the Turkish capture of Smyrna at the end of the
Greco-Turkish War. Following the death of his father in 1922, Alec and his mother moved to the UK in 1923. Alec studied engineering at
Battersea Polytechnic in London. He failed his mathematics exams three times and subsequently called
pure mathematics 'the enemy of every creative genius'.[
citation needed] After
Battersea Polytechnic, Alec decided to enter the
University of London External Programme to complete his university education.
