Given we can't see the pot/container difficult to answer... A rhodo of that size much prefers to be in the ground!

Thanks Moon growe ,I don't know if the new pic helps with the size of the pot. This was the plant when I bought it in 2011 and put it in the pot it is in now.
Would it be ok in the ground as I thought they need ericacious compost?

If the rhododendron is in that small ornamental wheelbarrow along with other plants then, yes it needs to be in a larger container. Leaves drooping down can be an indication of lack of water. I'd repot the rhodo on its own in ericaceous compost in a larger pot or container. Another thought does that ornamental mini wheelbarrow even have drainage holes as another cause of yellowing leaves and leaf droop is, oddly enough, the shrub sitting in water. In reality you are trying to grow something that, in nature, grows part way up a hillside in acidic soil with plenty of moisture that is also reasonably free draining.

If those are limestone chippings, that is not going to help the Rhododendron if put in the ground.

Indeed not Kildermorie... Nanjo I suspect you are simply going to have to get a larger container just for the rhododendron.

Sorry Moon growe ,I should have said that the Rhodo is the one in the black pot by the far fence at the top of the pic....it is in ericaceous compost and well watered.
Kildermorie,the stone chippings are cotswold stone so no idea if they are limestone.

Nanjo the rhododendron in the black pot looks fine, so far as I can see from that distance... I would suggest that you raise the pot up on 'feet' so that the compost can drain more easily. Also Cotsowld stone is pure limestone so this could be affecting the Rhodo as the pot is sitting directly on it.

Thanks for your help, I think I will make a new bigger container for it and also make feet. :-)

Good luck!