I was only searching for stuff about Milk Stout and look what comes up. I suppose it was inevitable, what with the folk stories you hear time and again about farmers feeding beer to all manner of beasts. From Life, March 22, 1948.
This is of course the kind of silly story that papers love, in 1948 and today. Those shouting that beer needs to get into the mainstream media could do well to reflect on that: Cows drinking beer is what the mainstream media are interested in.
You never saw it in the mainstream press when BrewDog put pale ale on a ship, or aged stout with berries in an Islay cask, or blended two double IPAs to try to achieve new flavours. You did hear about it when they made "the strongest beer in the world", because that's the type of trash the press want to write about. Who's really to blame, BrewDog or the mass media?
But this story, apart from being silly, is interesting because we actually find out what kind of beer is involved, and there's even a lovely picture of bottles with nearly-legible labels. Oat Malt Stout (not Oatmeal). That narrows it down a fair bit. The label resembles the Tetley's huntsman but the lettering above the type of beer seems to be two words. I remember somewhere reading that some other brewery also had a huntsman logo … [edit: Puzzle solved. It was Eldridge Pope. Thanks to Callum]
Should be easy: A brewery in Hampshire or thereabouts, that in 1948 had an Oat Malt Stout with a huntsman on the label. There's a prize for the right answer. A bottle of Milk Stout. Or Oat Malt Stout if you prefer.