It looks quite young so could be juvenile colouring. My photo below shows an adult on the right with a juvenile that's probably slightly older and you can see the brown is just starting to come through. This was taken from a couple of feet away and they were never that bothered about me.
If you can keep your head, while those around you are losing theirs, you may not have grasped the seriousness of the situation.
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Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.