Barm

n.

A yeast substitute obtained through the fermentation of potatoes. This produced an alcohol by-product. There were two men that used hand out this by-product to the local alcoholics. They were nicknamed "The Popes" because of the number of men they cured!

Let Lawrence Muck translate it to posh English for you
Lawrence Muck

Do excuse my tweed. Would you like me to translate 'Barm' in use for you?

I am reliably informed that the potato barm cured more gentlemen than the Pope himself.