Though, as with everything, it's a bit more complicated than that. UK brewers definitely weren't keen on lining casks with pitch, as was the Central European practice. They reckoned pitch was the source of the onion flavour they detected in Lager. But they did use other materials to line casks. Though much more common was the use of unlined casks.
This is one of the first mentions I've found of lining casks in the UK. In this case with some sort of enamel. It's a bit vague about the composition of the enamel. Perhps it was a trade secret.
"Enamel for Casks.The article reads a bit like an advert for Messrs. Crawford & Co.'s enamel. Was it really as wonderful as made out?
Some short time ago we detailed the necessary treatment of cask plant, and pointed out that we had tried nearly all the chemical agents advertised for the purpose of restoring musty and stinking casks, but with no result that we could safely recommend to our readers. We are, however, now pleased to say that since the appearance of our previous note, we have conducted experiments upon a footing entirely different from those previously carried out. The experiments we speak of have been in the direction of the application of enamels. Now, from a practical point of view, we know many brewers who have experienced great benefit from the use of this class of material, but it was with reluctance that we ventured to give it a trial, since we were under the impression that the various forms of enamel were, more or less, all of the same character, and knowing that alcohol has a decided effect upon the majority of them, and that acetic acid has a still greater effect, we were sceptical of the result, but we are all liable to mistakes, and it is in this particular that we made one, for the simple reason that we have just analysed one patent enamel, and find that these two powerful solvents, alcohol and acetic acid, have no action whatever upon it. Therefore, from an experimental point of view, we find that it is without a rival, and from information received, we are bound to admit that it is an excellent material, not only for the purpose of curing musty and stinking casks, but for the purpose of preserving casks, which are not in such a bad state, since the enamel in question lengthens the life of cask plant to a somewhat considerable extent. The enamel we speak of is patented and manufactured by Messrs. Crawford & Co., to whom we refer our readers for particulars, and although our having to go to press prevents us discussing this subject further, we will nevertheless, in a future issue, detail the enamel’s practical application, since we are certain that the majority of fretful causes of beer, combined with acidity and turbidity, are due to faulty cask plant, which we have no hesitation in saying, could be readily avoided by the use of such an enamel as the above."
"The Brewers' Guardian 1889", 1889, page 370.