I was feeling in a good mood the other day, and the expression happy as Larry sprang to mind (the alternative, like a pig in shit, being perhaps a little coarse). I was wondering about the origin of the phrase. Phrases.org here has two suggestions, about a Australian boxer Larry Foley, and it being derived from larrikins (hooliganism), which is presumably amusing to the perpetrator.
Are either of these correct? Does anyone have any other suggestions?