Green’s Dictionary of Slang

1. far from it, ‘not likely’.

1862		‘Artemus Ward’ Artemus Ward, His Book 60: She ceased my coat tales & in a wild voise cride, ‘No, Ile never desart you —let us fli together to a furrin shoor!’ Sez I, ‘not mutch we wont’!
1868		H.L. Williams Black-Eyed Beauty 42: You never don’t get your ‘paper’ honestly! by much!
1873		Atlanta Constitution 12 Mar. 1/3: When she is asked if she will go with you to some place, [she replies] ‘not much’.
1883		G.W. Peck Peck’s Bad Boy and His Pa (1887) 152: ‘I thought may be you had killed your Pa.’ ‘Not much. There will be more than three hacks when I kill Pa, and don’t you forget it.’.
1884		Sporting Times 25 Oct. 2/4: Was Hamlet mad? Not much.
1891		Sporting Times 17 Jan. 1/2: ‘Me ride alone with the head blooming bobbie of all London? Not much’.
1893		H. Lawson ‘Mitchell: a Character Sketch’ in Roderick (1972) 134: But Mitchell’s head wasnt go’ne — not much.
1900		Bulletin (Sydney) 27 Jan. 15/2: W’y Gawd blime, when Lord Methuen’s push give ’em such L in the trenches do you think the beggars would give way? Not much!
1907		Harrington & LeBrunn [perf. Marie Lloyd] Who are you getting at, eh? 🎵 He said to me, ‘You’re married now I suppose.’ / I said, ‘Married? not much.’ and turned up my nose.
1908		S.E. White Riverman 17: ‘When that sheriff comes, with or without a posse, I want you to go peaceably.’ [...] ‘Cave in? Not much!’ cried Purdy.
1915		S. Ford Shorty McCabe on the Job 170: ‘But I expect Mr. Leavitt will be up.’ ‘What, alone?’ says she. ‘Him? Not much!’.
1924		C.J. Dennis ‘Stone the Crows’ Rose of Spadgers 121: But even if she don’t I would n’t care— / Not much.

2. in ironic use, very much, very likely.

1884		E. Nye Baled Hay 163: Not much, Mary Ann!
1887		F. Francis Jr Saddle and Mocassin 144: ‘Sam Rider? Isn’t he in the valley?’ ‘Not much!’.
1916		Sun. Times (Perth) 30 July 1s/2: We don’t admit such blighted rot, / Not much! And strike me pink! who cares.
1925–30		J. Garber ‘You Don’t Like It – Not Much!’ 🎵 Say, when I hug you and when I squeeze you and when I please you and such, / Say, you don’t like it, no, you don’t like it, not much!
1930		J. Lait Put on the Spot 24: ‘Did you see the face on Kinky t’-night, when he saw us come in the Devil’s Hall?’ [...] ‘Did I? Not much.’.
1955		‘Hal Ellson’ ‘Tell Them Nothing’ Tell Them Nothing (1956) 1: It’s like they ain’t going to make it. Not much.
1957		H. Simmons Corner Boy 180: He didn’t want Georgia, not much he didn’t.
1968		S. Gore Holy Smoke 52: But the Lord [...] steps the storm up to about force ten. And did she get to be a stinker – not bloody much she didn’t!
1985		S. Berkoff West in Decadence and Other Plays (1985) 109: Fancy her / not much I don’t half.