Green’s Dictionary of Slang

jack (jones) adj.

alone.

1892		‘Fanny Flukem’s Ball’ in Bird o’ Freedom (Sydney) in J. Murray Larrikins (1973) 40: The Tempe blokes just stopped one each / And then they guyed a whack. / ‘It isn’t on our programme / And, Gor’ bli’ me we are jack.’.
1925		(con. WWI) Fraser & Gibbons Soldier and Sailor Words 130: Jack Jones: Alone.
1963		C. Wood ‘Prisoner and Escort’ in Cockade (1965) I iii: And me here – Jack Jones.
1971		J. Jones Rhy. Cockney Sl.
1981		P. Wright Cockney Dialect and Sl. 99: One instance is Jack Jones ‘alone’ (sometimes shortened to on ’is Jack ‘on his own’).

In phrases

on one’s jack (jones) (also on one’s j’s, on one’s jacks, on one’s jacksy)

on one’s own, by oneself.

1930		(con. 1910–20s) D. Mackenzie Hell’s Kitchen 119: On his Jack ... alone. [Ibid.] 165: The Other Bird, who did the job on his ‘Jack Jones’ (alone), was afraid of not getting the value of the things.
1938		L. Ortzen Down Donkey Row 110: Well you see if yer kin git on wivaht me! You ’ave a crack at doin’ the job on yer Jack Jones.
1943		M. Harrison Reported Safe Arrival 19: Well, me an’ ole ’Itler’s goin’ to ’ave a bit of ancient ’ist’ry on our Jack Jones. [Ibid.] 61: ’E gets crackin’ all on ’is Jack Jones.
1943		R. Llewellyn None But the Lonely Heart 21: I told the soppy cow what would happen to her if she worked on her Jack.
1958		F. Norman Bang To Rights 11: I’ll be in a peter somewhere in Wandsworth all on my jack. [Ibid.] 30: It is a strange feeling being locked up on your jack.
1961		T. Taylor Baron’s Court All Change (2011) 152: I couldn’t face the law on my Jack Jones.
1963		C. Wood ‘Prisoner and Escort’ in Cockade (1965) I iii: Leaving me here on my jack with him – I’m not sure it’s not against regulations.
1977		D. Powis Signs of Crime 189: Jack (Jones) Alone: ‘He’s all on his Jack.’.
1979		R. Barker Fletcher’s Book of Rhy. Sl. 39: Those who are on their Jack Jones.
1984		‘Derek Raymond’ He Died with His Eyes Open 135: You’ve no idea how grotty a place looks with just a bloke on his jack living in it.
1992		A. Duff One Night Out Stealing 149: He felt his face redden but he had to finish it even though it ended lamely — all on my jacksy.
1993		I. Welsh Trainspotting 5: Next time one ay us ur walkin hame on oor jack Jones, wi git hassle fi these wee radges.
1997		C. Newland Scholar 267: I ain’t raisin’ no kid on my jacks.
2001		(con. 1981) A. Wheatle East of Acre Lane 209: Been on my jacks since two, man.
2001		M. Coles Bible in Cockney 83: Let’s pop off on our Jack for a while and have a little rest.
2004		Shystie ‘Intro’ 🎵 on Diamond in the Dirt [album] I’m on my Jack Jones.
2011		J.J. Connolly Viva La Madness 45: I always head off on my jack, mid to late February.
2012		(con. 1980s) I. Welsh Skagboys 334: A man can only be himself so long as he’s on his Jack Jones.
2016		Skepta ‘Corn on the Curb’ 🎵 Where are you, though? Who are you with? I’m on my Js, blud.
2017		1011 ‘Tek Bo Chat’ 🎵 Been up and down on the opp block on my Jack Jones man I like to wander.