During the seventies I had to take regular samples of effluent from the two major breweries in Burton-on-Trent. I often noticed big Hovis flour tankers making deliveries to what was then the Bass or Allied Breweries plant – I can’t remember which.
Those of course were the days of ersatz beer made cheaply from fermented starches such as flour with caramel added as brown colouring to make up for the lack of malt and saponins (natural soaps) to put a creamy head on the final product.
I’m not sure how different it is these days, but I suspect there are still some pretty grim brews sold under the misleading name “beer”. If you fancy a drop of real ale, then stick to the smaller brewers may be the best advice. Otherwise you really cannot be sure what you are drinking.
Better still, take a trip round the brewery and keep a lookout for Hovis tankers.