Green’s Dictionary of Slang

a talkative boy.

c.1698		B.E. Dict. Canting Crew n.p.: Prateroast a Talking Boy.
1725		New Canting Dict. [as cit. c.1698].
1737, 1759, 1760, 1776		Bailey Universal Etym. Eng. Dict. [as cit. c.1698].
1785, 1788, 1796		Grose Classical Dict. of the Vulgar Tongue.
1809		G. Andrewes Dict. Sl. and Cant.
1811		Lex. Balatronicum.
1823		Egan Grose’s Classical Dict. of the Vulgar Tongue.
1835		G. Kent Modern Flash Dict. 25: Prate roast – a loquacious fellow.
1848		Flash Dict. in Sinks of London Laid Open [as cit. 1835].
1859		Matsell Vocabulum.
1885		‘Lela’ in Maitland Mercury (Aus./NSW) 31 Mar. 2: The arch gonnoff is dusty, you’d better wish. If he rats you are a prate roost [sic], you’ll get put to bed with a shovel.