As so often with camp and children's songs, "Down the Dark Alley" derives from a bawdy song sung by soldiers. I don't know its origin, but the first I have found it printed is in "Mess Hall Songs of the RAAF," a 1945 collection of airmen's songs during World War II. You can find the songbook at:

http://www.horntip.com/html/books_%26_MSS/1940s/1945-09-00--1961_mess_songs_and_rhymes_of_the_RAAF_(mimeo)/index.htm

It next turns up in Korea as sung by members of the Royal Australian Air Force during the Korean War:

http://www.horntip.com/html/books_&_MSS/1970s/1971ca_songs_my_mother_taught_me_(mimeo)/index.htm

and after that seems to have entered children's tradition in the UK and Oz at least. Anyone know any versions from the US, Canada, or other different locales? I don't find it in a hasty survey of Cray's The Erotic Muse, the Vance Randolph collection or Logsdon's The Whorehouse Bells Were Ringing, three good sources of such songs.

Bob