Green’s Dictionary of Slang

1. a drunken layabout.

1876		NSW Parlt. Jrnl 26:2 605: The woman complained that it was occupied at night by a lot of ‘Johnny Warders.’ This term is derived from one Johnny Ward, who at one time kept a low public-house at the wharf, where he dispensed cheap rum to his customers.
1880		Bulletin (Sydney) 4 Dec. 4/2: The title ‘Johnny Warder’ applied to vagrants of a certain decsription, had its origin in the fact that a man named John Ward, who kept a public house [...] used to allow persons of that class to congregate and sleep in a large room adjoining his hotel.
a.1882		Sydney Sl. Dict. n.p.: Johnny Warder, ‘an idle drunkard who hangs about pub corners looking for a drink – called after a publican named John Ward who formerly kept a low house in Sydney noted for that species’.
1902		Truth (Brisbane) 13 Apr. 7/3: Before him one morning, for the usual offences, language and liquor, was an old ‘Johnny Warder.’ She was begging hard for another chance.
1910		Truth (Brisbane) 15 May 1/3: [T]he real meaning of the word Wowser is as well-known as are the meanings of such words and phrases as [...] Johnny Woodser, Johnny Warder, Dicken, ‘I don’t think,’ and ’I should - smile’.

2. anyone who drinks alone, a drink that is taken by oneself.

1959

Baker Aus. Speaks.