If you are genuinely exempt from wearing a mask, is there some established manner in which you can inform anybody who might challenge you about it?
Where I am, in the last two months, I have only seen one adult not wearing a mask when they 'should' be - and everybody knows why he isn't*.
* He is completely bonkers and believes every conspiracy theory known to humanity, including the Illuminati fabricating this fake pandemic to allow them to insert microchips into you via the "vaccine".
Would that be generally considered to be a reasonable excuse?
I have also had this conversation with someone in Hampshire, a couple of days ago.
He asked me "Are people wearing masks over there?"
Yes, where they should be.
I don't think there's any point.
Well, there is - and there's no harm in doing it anyway, is there?
There's no point, if they don't wear them all the time.
Well, it doesn't matter anything like as much outdoors, though a lot of people here will leave them on if the next shop is close.
They should wear them in the street, too - if you're just putting them in your pocket, there'll be all sorts on it.
Do you wear a mask in a shop.
Yes.
Do you wear a mask in the street?
No
Where do you put the mask when you're in the street?
In my pocket.
...at that point, I gave up...