It is probably too dry and this maybe because it is potbound. The pot would be full of roots and water just runs off the surface. I see that you have a nice garden behind it. Could you consider planting this one in the ground and buying a smaller one for the container?

Thankyou Bulbaholic, that's a good suggestion. I have room to plant it in the ground. Should I hard prune it or not? The sticks that are left are 85% hard wood... I'm not sure how to encourage new growth.

Guessing that the planter is fairly solid with roots, I would take it out of the planter and put it in a bucket/bath of water for a few days. Then start to pull the rootball apart to loosen roots. Don't worry about being gentle, you are in an A&E situation doing whatever you can to save a life and the rhodo can take it. Then put it in a good sized hole and keep it watered - and just hope. I wouldn't prune it.

Bag this one - it's all over. You can still pick up a nice healthy one from the garden center at a bargain since planting season is winding down. Plant that in the garden. Not only pot bound, but if the soil isn't acidic, it won't be able to take up water or nutrients.

Rhodos need constant moisture, acidic medium & plenty of room and more so as it grows bigger which is indeterminate - not a good choice for a planter in my opinion. The dwarf varieties like Scarlet Wonder, April Rose, Blue Tit Magor, Christmas Cheer, Else Frye are better suited for pots, very big pots.

Thanks everyone for all the help and advice. Onwards and upwards.... x