Green’s Dictionary of Slang

a general excl. of dismissal or disbelief, ‘you must be joking!’.

1959		W. Hall Long and the Short and the Tall Act I: Well, flipping stroll on! That’s all. Stroll on.
1963		C. Wood ‘Prisoner and Escort’ in Cockade (1965) I iii: Stroll on.
1977		G.F. Newman Villain’s Tale 81: ‘Yeah, I got ’em.’ Gibbs let out a heavy sigh. ‘Fucking stroll on. We had a bit of luck here, I’d say, Billy. A right bit of luck.’.
1989		T. Blacker Fixx 143: Marc Shelley, a grown-up? Stroll on.
1993		I. Welsh Trainspotting 135: Ye dinna see any fat bastards on tv footage fi Ethiopia. Dae they no huv glands ower thair? Stroll on.
2001		K. Waterhouse Soho 43: This was definitely one for the lads back at the Metro. Blurry pub turned into a blurry mortuary, stroll on.