Conversation so far:
Where did Bernard Lewis go to school?
He attended the School of Oriental Studies at the University of London.
What did Bernard Lewis study?
Bernard Lewis graduated from the School of Oriental Studies at the University of London with a BA in history with special reference to the Near and Middle East.
Did Bernard Lewis study anywhere else besides the School of Oreintal Studies?
Bernard Lewis undertook post-graduate studies at the University of Paris.

Question: When was that?
Self-contained rewrite: When did Bernard Lewis study at the University of Paris?