Hmmm...not too happy, is it. Mine thrives on pruning, so why not give it a good prune, feed it and hope for the best? It isn't the best time to prune it, but I think I'd risk it.

Can I ask how old it is Lincslass?

About 8/10yrs Drc and was very happy in that spot.
Thanks Spritz...

It has substantial growths of lichen, they can take hold on on slow-growing woody plants, I have it this year on my Hibiscus.
While the lichen will not kill your Berberis, it has had an absolute field day on it, because the shrub is suffering from some other problem?
Generally lichen-covered shrubs are either choked by weeds/grass or have been neglected/damaged and are thus failing to grow at a decent rate each year. I do think yours is very small for its age?
I would clear the ground underneath and fork in a general fertiliser and then mulch and I would not prune yet and hopefully the shrub will start to outstrip the lichen.

Thanks Drc, I`ll have a go at that tomorrow, its in the middle of one of my flowerbeds but there is space under and around it for me to be able to do that....

I think its worth a do Lincslass

I would also pull out (maybe transplant?) everything within 6 inches of the edge of the bush, to reduce the competition. 2-3 tablespoons of molasses in a gallon of water would probably do it some good, too.

Thankyou Tugbrethil...

Has it recovered, now we have had some rain? I have been amazed how some of my plants have recovered now, after drooping during the dry summer even though they were watered frequently.