Since there were no chloroflurocarbons on board with the norman invaders at Prevensky, there was no ozone hole. The ozone hole measured zero Square kilometers in 1066
The ozone hole shrinks and grows depending on season... chloroflourocarbons or no chlorflourocarbons.
As far as anyone knows there has always been a seasonal thin spot down there... the atmosphere plays differently in the southern hemisphere where in contrast to the north, there is uninterrupted open sea all around Antarctica and nothing to slow air down. That causes a chain effect even into the layers above.
The ozone hole hysteria was due to new data coming in from a new satellite being used politically. They neglected to inform anyone they had no old data to use as a baseline.