Read this and answer the question. If the question is unanswerable, say "unanswerable".

In the past, people at Eton have occasionally been guilty of antisemitism. For a time, new admissions were called 'Jews' by their fellow Collegers. In 1945, the school introduced a nationality statute conditioning entry on the applicant's father being British by birth. The statute was removed after the intervention of Prime Minister Harold Macmillan in the 1960s after it came to the attention of Oxford's Wykeham Professor of Logic, A. J. Ayer, himself Jewish and an Old Etonian, who "suspected a whiff of anti-semitism".

In what year did A.J. Ayer become a Professor of Logic at Oxford's Wykeham?
unanswerable