Read the Operation History section here:
http://en.wikipedia.org/wiki/Westlan...lwind_(fighter)

Only three Whirlwinds were used during Bob time by 263 squadron of which one crashed on August 7th, 1940. This squadron only finished converting to Whirlwinds in December 1940. I'd say there are more urgent planes for Bob such as the Hampden
http://en.wikipedia.org/wiki/Handley_Page_Hampden