Green’s Dictionary of Slang

1. (Aus.) the post, the mail.

1905		Duke Tritton’s Letter n.p.: Well China, this Don’t Forget Her is getting long and I am out of Nails And Screws, and I have to catch the Holy Ghost, so will end off with all the best from, Your old Thief And Robber.
1932		‘P.P.’ Rhy. Sl.
1935		A.J. Pollock Und. Speaks.
1960		J. Franklyn Dict. of Rhy. Sl.
2002		Pete’s Aussie Sl. Home Page 🌐 Holy Ghost (1): the post, mail.

2. the post, i.e. the start-line for a horserace.

1944		Maurer & Baker ‘“Aus.” Rhyming Argot’ in AS XIX:3.
1969		S.T. Kendall Up the Frog.
2002		B. Kirkpatrick Wicked Cockney Rhy. Sl.

3. toast.

1960		J. Franklyn Dict. of Rhy. Sl.
1962		F. Norman Guntz 50: Little bits of holy ghost with sardines and stuff on them.
1968		J. Alard He who Shoots Last 74: And bring us plenty of holy ghost and don’t spare the butter.
1983		R. Aven-Bray Ridgey-Didge Oz Jack Lang 31: Holy Ghost Toast.
2002		Pete’s Aussie Sl. Home Page 🌐 Holy Ghost (2): toast.
2011		J.J. Connolly Viva La Madness 132: Slice after slice of buttery holy ghost.