By Goodwood
United Kingdom 
tugbreth from goodwood had tree for 3 years in large pot has been ok with plenty of berries but leaves shriveled and berries very small and dried up last few weeks no sign of what has caused this condition
23 Sep, 2017
Answers
I answered on your original question, and finding out that it is in a pot adds a few extra hazards. Since the roots of plants in pots can't go looking for water, and the canopy of the tree may well shield the compost from the rain, potted plants are very subject to drought damage. A missed watering or two often results in sudden death.
For the future, Goodwood, you can give additional information by posting a comment on your original question. That way, all of the people who commented on your question will be notified, and we can figure things out better.
23 Sep, 2017
does it look as if it has been caught by a fire? if so probably fireblight. if so then it needs removing and burning or bagged and not composted.
google images of fire blight on cottoneasters.
23 Sep, 2017