One of the grievances that led to what would afterward be known as the 'Peasants Revolt' (1381) was the populace around St. Albans having their own quern stones to grind their own grain to make their own flour to make their own bread.
The Abbey owned a Mill that had previously been the only means to grind the wheat into flour, and had charged a premium for its service. Everyone would bring their wheat to be ground @ the Abbey, and a toll would be payed for the privilege.
Fast forward to the mid- 14thC and hand querns become hugely popular because price-fixing has become out of hand. Grand Abbeys are so money-grabbing that they try to make the ownership of querns illegal so that they can regain a monopoly on milling, just like it was before the Black Death made all these peasants aware of their power. In an episode that highlights just how much organised religion was organised against the people it represented, the Abbey, with Royal backing, confiscates privately owned mill-stones.
To truly represent the horror they have now become, the Abbey uses the confiscated mill-stones to pave the road that the dispossessed will need to take to make their way to their local church. Where they will hear sermons that speak of another world.
During the 'peasants' revolt - huge swells of people, many of them far from 'peasants', mass on the outskirts of London. Many of them are just there because they want to be able to grind their own corn.
The people who are there from St. Albans have ripped up those quern stones from the road.