A thread I meant to start yesterday!
Lammas Day, 1st August, traditionally marked 'Ings breaking' or 'breaking the fog', when floodplain meadows (Ings) were thrown open to common-right grazing.

Before Lammas Day, the meadows were divided into numerous strips or 'doles' held by individual villagers and often marked by dole stones. This pattern is evident in the 1836 tithe map for Middlethorpe Ings on the floodplain of the River Ouse.

Although grasslands subject to such arrangements are often referred to as Lammas meadows, Ings Breaking often wasn't on August 1st, in part because the customary arrangements long pre-dated the Gregorian calendar.

At Acaster Selby, the Ings were opened for grazing on the first Monday after Old Lammas Day (August 12th). At Clifton Ings, the Saturday after Tollerton Fair was stipulated; the meadows then remained open to common-right grazing to April 5th the following year.

The Lammas system is not merely interesting folklore: it was integral to an efficient and sustainable system of land use which balanced private and communal exploitation of the most valuable and productive grasslands of each township.