Corrections and comments follow:
In the England that he abandoned, George Bidwell isn’t known; in the Poland that he chose, he isn’t remembered. (These corrections support the parallel structure of your first sentence -- a very effective opening! Please note that for this purpose, the semicolon now replaces your former comma, and that your dash in the second clause has been replaced by a comma.) In 1949,
heBidwell decided that the rest of his life would be devoted to a new homeland. He left England, where he had been a journalist and a bank clerk, for Poland, where, without even knowingany prior knowledge of the language, he later became a naturalized Polish writer, and publishedeventually having published over 60 novels and historical books in his adopted language. (Did Bidwell do the actual publishing? - Probably not; thus the suggested revision " ... having published ..." here. Also, "... in his adopted language" is added here simply to emphasize Bidwell's accomplishment as a naturalized Polish writer.) Many of themthese works are still available on the Internet.
Even so, the most recent edition of “The Lexicon of Polish Writers” (Please provide the year of publication here within parentheses.), released by the Cracovian Scientific Publishing House, doesn’t mention him at all. Apparently, the Poles
perceiveconsider him to have been primarily an English writer. But what do we really know about George Bidwell?
At the end of the year 1945, Major Bidwell appeared in the London Office of the British Council. He had been called by Colonel Kenneth Johnston, the head of the European Institute department engaged in the promotion of British culture abroad. Bidwell, the ex-chief of the British Army supply in the Near East and participant in the Battle of El Almein, had worked for the British Council for two years.
(Set your dialogue -- a very effective technique to advance your essay/narrative -- off in a separate paragraph.)
“It seems that during your service in the Near East you were in touch with some Polish people?” (Comma deleted here.) asked Johnston. Bidwell confirmed. “Then I have something to offer you. We lack a manager in Poland, would you agree to become one?” (Period deleted here.)