Wonk was the name of a koalabear in an old series of children's books.

Because of the overwhelming resemblence and his portly physique, Norman Lamont (an ill-fated and rather hapless Tory Chancellor of the Exchequer) was often referred to as Wonk. It is highly unlikely, however, that Wonk-the-koala would ever have consorted with Miss Whiplash or bounced cheques at his local offlicence.