Green’s Dictionary of Slang

a show-off, anyone particularly pleased with themselves and keen to ensure that everyone knows it.

1975		‘P.B. Yuill’ Hazell and the Three-card Trick (1977) 25: Jack the Lad in the estate agents had given me a string with three keys.
1983		J. Sullivan ‘Thicker than Water’ Only Fools and Horses [TV script] He used to be a right Jack the lad, all flashy shirts and gold cuff-links.
1989		in G. Tremlett Little Legs 15: Jack the Lad, having a quiet smoke.
1989		R.G. Barratt ‘So Why Doesn’t Jack the Lad Get a Real Job?’ in What Do You Reckon (1997) [ebook] [People] think you’re Jack The Lad, having a top time getting paid millions for doing nothing.
1992		R.G. Barrett White Shoes 85: KK lapped it all up, playing Jack the Lad.
1999		Observer 18 July 31: He was perceived to be a bit of a jack-the-lad.
2000		Guardian 23 Mar. 28: Smugglers were gangs of hardened criminals [...] rather than ‘Jack the Lads’ doing a few friends a favour.
2005		P. Howard Curious Incident of the Dog in the Nightdress 20: I’m playing the big-time Jack the Lad.
2108		(con. 1950s) M. McGrath Pie & Mash 134: Bit of a chancer is Charlie. Bit of a wheeler-dealer, bit of a Jack the Lad.