There is a picture of him (out of uniform) in a 1936 edition of Flight magazine (I'm afraid the article has to be loaded a page at a time):
http://www.flightglobal.com/FlightPD...20-%201816.pdf
http://www.flightglobal.com/FlightPD...20-%201817.pdf
http://www.flightglobal.com/FlightPD...20-%201822.pdf
http://www.flightglobal.com/FlightPD...20-%201823.pdf
http://www.flightglobal.com/FlightPD...20-%201824.pdf
The picture is on the second link (the missing pages between links 2 and 3 were adverts)
EDIT: oops, just noticed that there is another picture of him on page 1 too