He or she has signed internally one of the wings of our Hawker Hurricane aircraft, a typical thing for builders to do.
Have you been able to check company records ?
Was the person a civilian living in the local town ? Phone directories, electoral rolls, immgration records might help.
run the name through a genealogy search engine for a soundex, for variations of spelling. Ellis Island Records or JewishGen might bring up something. You won't find the person, but you might find the name.
Have you found a website for Thunder Bay and posted a message ?
Have you posted a message on the various WWII websites ?
Maybe the Imperial War Museum, London can offer you some tips.