Although Stuart the miller makes wheat, spelt and rye flour these days, the Heron Corn Mill must have spent a large part of its illustrious history grinding oats. Oats were the main local grain, and many local place names include "Haver" (the old word for oats) - Haverbrack, Haverthwaite, Haverigg etc.
Dictionary definition of "haver" -
Borrowing from Scots haver, from Middle English haver, from Old Norse hafri (“oat, oats”), from Proto-Germanic *habrô (“oat, oats”), from Proto-Indo-European *kapro- (“goat”). Cognate with Dutch haver (“oats”), cognate with German Hafer (“oat”)
When the more efficient but less gentle steel roller mills came onto the scene, the traditional slow grinding stones of the Heron Corn Mill could not compete, and were largely relegated to processing oats for animal feed. The Heron as we know it is specifically kitted out for milling oats. One set of stones is lighter than the others, and was used to crack the hard outer shell on the oats. The softer grain inside was then ground on a heavier set of stones.
One baker asked if you could make bread with oats. When I did a bit of Googling round this question, I found that the real answer is no, because oats do not contain any gluten. People with serious gluten problems have to be careful with oats because they tend to get contaminated with other grains like wheat, but the oat itself is a gluten free zone.
Googling searching is now so clever that you can just type things like "gluten in oats" and it comes back with all the information you could possibly be looking for, including a link to the coeliac society.
This doesn't mean, of course, that you can't use oats in bread, or as a coating for bread. But you do need something else to provide the gluten to give the bread a lift.
Unlike oats, rye does contain gluten. But it is the wrong kind of gluten apparently, and doesn't trap the gas the way the gluten in wheat does.
When yeast breaks down flour, it gives off gas. The tangle of gluten strands in the dough catches the gas and the dough rises. No gluten, no rise.
So if you want to make bread with oats or rye, it is pretty well certain that you will need to mix the grain with something that contains the right kind of gluten - probably wheat.
And if you want to make bread without gluten - well, good luck with that.
It's not immediately obvious that there is fat in grains, but if you Google for "fat in oats" you will see it is about 7% whereas "fat in wheat" is about 2.5%. So adding some oats to a loaf, while it won't improve the rise, might well improve the richness of the bread.
The more protein there is in flour, the more gluten it will produce when you make bread with it. This is why many flours boast about their strength - basically the amount of protein they contain.
According to the Encyclopedia Britannica -
Not everything is important
We had a go at getting thumb-shaped bubbles into our flutes last time we baked at the Heron Corn Mill. It was a miserable failure. But not to worry - the flutes tasted pretty good, even if they weren't as crisp as they should have been. You can spend a lot of time chasing perfection when making bread. But it's alright to get a result that is just OK. It's bread made with our own hands, and with good ingredients and good intentions. That really IS important!