haha... that one's easy.
That's "Botany Bay."

Farewell to old England forever...
farewell to my home town as well
farewell to the well known old bailey
where i once used to look such a swell
singin' toorilai oorilai addity (sp lol)
singin' toorilai oorilai ay
singin' toorilai oorilai addity
for we're bound for botany bay


it's about people being sent as convicts to Australia.