Green’s Dictionary of Slang

blitherer n.¹

a silly fool.

1899		C.J.C. Hyne Adventures of Captain Kettle 298: ‘Out, you blitherer,’ he shouted, ‘and save your mangy life.’.
1908		Bulletin (Sydney) 8 Oct. 28/2: Also Yarraville impressed its superiority on ’Scray from the start, and thereby so depressed Elizabeth and William aforesaid that after a few preliminary adjurations to ‘Root ’em up, Juniors!’ ‘Slob into it, you blitherers!’ they relapsed into moody and depressing silence, heedless even of the ‘chucking off’ of the Yarraville barrackers.
1909		Wodehouse Mike & Psmith [ebook] ‘I fear Comrade Jellicoe is a bit of a weak-minded blitherer—’.
1910		Wodehouse Psmith in the City (1993) 43: The sympathetic cooperation of that record blitherer, Comrade Jellicoe.
1924		G.H. Lawson Dict. of Aus. Words And Terms 🌐 BLITHERER–Annoying person.
1961		‘Frank Richards’ Billy Bunter at Butlins 213: It’s not yours, you blitherer!