Question:
Which employer did Jonathan Bennett work for in Apr, 1957?

Context:
 Jonathan Bennett works for University of British Columbia from Jan, 1970 to Jan, 1979. 
 Jonathan Bennett works for University of Cambridge from Jan, 1956 to Jan, 1968. 
 Jonathan Bennett works for Simon Fraser University from Jan, 1968 to Jan, 1970. 
 Jonathan Bennett works for Syracuse University from Jan, 1979 to Jan, 1979.

Answer:
University of Cambridge