Unfortunately I cannot see the pot in your photo, so I'll assume its the same size as the other pot, but how long has the one that's lost its leaves been in the same pot? It looks to be a taller plant, and from the little bit of leaf I can see, it would appear to be suffering from insufficient root room and insufficient water, although the one often leads to the other...

Thanks for the quick reply. The plant has been in the pot for about three years but does get fed. It is also smaller than the other bush but with one tall stem. It was the pattern on the leaves that I was concerned about. They both get the same amount of water but I must admit it does not have a tray under it like the other one. Any ideas of how to treat it now?

Trying to say thanks but not sure how to send it. If possible see my previous comments to you.

It's okay, I can see both your responses - I'd soak it well, then turn it out of its pot to see if its rootbound, or if there are any invaders in there (ant's nest for instance). If it's rootbound, either plant in the ground (but it needs acid soil so that might be an issue) or you need a larger pot - at least 2 inches larger all round. When there's a very high ratio of root to compost, there's not enough soil to hold onto moisture, so the plant gets drought symptoms. If the pot's really dry, stand it in a tray or something when you water and give it time to soak it up before turning it out...