Green’s Dictionary of Slang

preaching or speechifying, whether or not on religious topics; also as adj. and thus backform. tub-thump v. and n.

1786		Scots Mag. 1 Mar. 37/1: There were two Miss hoof-Sneckens [...] the eldest, her beauty doth chiefly consist / In a vulgar red check and a tub-thumping fist.
1843		Northern Star (W. Yorks) 1 July 4/6: ‘Neddy’ [...] and the Rev. Mr Massie, as tub-thumping corporal, still pipe their whistles.
1856		Liverpool Dly Post 3 May 2/6: That fine and highly laboured peroration concerning prostitution would have told with immense effect in his tub-thumping days.
1859, 1860		Hotten Dict. of Modern Sl. etc.
1864, 1867, 1870		Hotten Sl. Dict.
1874		York Herald 11 Aug. 5/5: It can never be attained by fanatical tub-thumping.
1883		Portsmouth Eve. News 13 July 3/4: If ‘anyone in black’ got up ‘tub-thumping’ or street preaching on the common he would want a license.
1889		Western Dly Press 28 Nov. 8/6: It is a mistake to suppose the Salvationists confine their efforts to drum-beating and tub-thumping.
1895		Crowe Aus. Sl. Dict. 89: Tub Thumping, preaching or speech making.
1897		W. Sickert The Sun 10 Feb. 4: It is like tub-thumping at Mr Balfour for miscalculations made by Lord Beaconsfield when Mr Balfour was in short frocks.
1907		Gem 16 Mar. 7: For all his tubthumping and ostentatious charity.
1913		Dundee Courier 19 Aug. 4/4: What a blare of trumpets, accompanied by much ‘tub thumping’ heralded his coming.
1925		S. Lewis Arrowsmith 246: Most of the things they tub-thumped in their campaign.
1938		longreach Leader(Qld) 1 Oct. 6/4: In those days he was always throwing out his chest and tub-thumping.
1947		B. Schulberg Harder They Fall (1971) 52: Nick pays me for the tub-thumping [...] This kind of talk I have to do for free.
1953		H. Tracy Mind You, I’ve Said Nothing (1961) 55: When all the breast-beating and tub-thumping are over [...] the Irish very coldly and shrewdly do whatever seems wise and convenient.
1977		R. Coover Public Burning (1979) 584: A real eye-opening, tub-thumping, hackle-raising sermon.
1999		Indep. on Sun. Rev. 3 Oct. 13: A tub-thumping sermon by Minister Farrakhan.
2000		M. Amis Experience 178: This particular tub-thump went back a long way.