I see. That makes sense about adding fresh beer or casking the beer with some gravity points left. So the carbonation of cask ale can happen in the cellar because there is sufficient yeast and fermentables allowed by the cask to overcome the decrease in fermentation caused by the lower cellar...
Pardon my ignorance of cask conditioning: what I don't understand is if Real Ale is conditioned at cellar temperatures, which I would imagine to be in the 40-50 degree F range, then how does the beer become conditioned? Especially since, according to the book How to Brew Real Ale at Home, which...