From "Baily's Magazine of Sports and Pastimes," XVII (1869), pp. 302-303, probably the best 19th Century description we're going to get of the singing of "Twankydillo" in a Yorkshire pub:

"The president rose and begged to observe that in his humble opinion the time for harmony had arrived. (Hear, hear.) He would, therefore, exercise his prerogative by calling upon his esteemed friend Mr. Turps to oblige with Twankydillo. (Vociferous applause, mingled with exclamations of 'A noble call!') Mr. Turps would have been most happy, he was sure, but he was at that moment suffering from cold. They would notice his hoarseness. ('No, no!' 'Come, Turps!') Well, he would fry, and if he broke down, they utterly spoilt the roundness of his 'period ' by a burst of applause.

"Mr. T.'s mode of carolling was peculiar. Unlike most amateur
minstrels, he refrained from fixing his gaze on a crack in the ceiling, or a globe of the chandelier. He bent his beaming face full on the audience, and with philanthropic impartiality distributed the beams all round. The effect of this effusion of gentle joviality was rendered more impressive by the waving of his right hand, not as a means of marking time, but to 'knock down,' as it were, the points of the song. Upon Mr. Macarthy and the other strangers present Mr.
Turps's gestures exercised a somewhat disturbing influence, by
causing them to burst forth into chorus at inappropriate periods. The touching expression of pity which the minstrel bestowed on the
erratic choristers failed to add to their composure. The aim of the
ballad was twofold: praise of the British blacksmith, and the glorification of the beverage manufactured by the British brewer. A
national song, my masters, the burthen whereof ran — phonetically —
something like this : 'Which it makes my bright ham-mer for to rise and to fall says the old coal to the young coal and the young coal
OF ALL' ['of all' fortissimo.]. Twankydillo, twankydillo, twanky-dillo, dillo, dillo, dillo, dil-OH! Oh, he who drinks good ale is the prince of good fel-LOWS!'

"The company were now warmed through and through, thanks to
the concerted rendering (' rendering' is the word) of the cabalistic
word Twankydillo. Everybody was delighted, because everybody
felt assured the grand success was chiefly due to his individual exertions."