You're right - it's an azalea or a rhododendron. :-)
I think the boundaries between the two are quite "porous" and some plants shuttle from one camp to the other. Didn't a whole lot of azaleas get renamed rhodo some time ago? I think it's doing pretty well if it's been in a tub for a long time, they're always going to do better in the ground, if your soil is suitable.

Thanks. The soil is pretty ropey here, think I might just give it a boost with some eracaceous feed then, as it's been virtually ignored up until now!

My neighbour has one and hers is a rhododendron :)

Have a look in the flowers, if there are more than five stamens then its a Rhodi, julien

It could be undernurrished if it has been in the container for a long time. Can you remove some, as much as possible, of the compost and replace it with fresh ericaceous compost. You can also but 'Rhododendron Food' in the GC. I have never used it but all our rhodoendrons grow in the ground.
I don't use the name azalea anymore. They are all Rhododendron species though of different forms.

Is that how you tell, Julien? You learn something every day! Must add that to my "useful notes"....

It has approx 11 stamens per flower so a Rhododendron then :-) (thanks Julien). Will try the ericaceous compost (thanks Bulbaholic) as I would probably need industrial lifting equipment to actually transfer it elsewhere!

As far as I'm aware, all azaleas have now been reclassified as rhododendron...

That is my understanding too Bamboo

The main practical difference between Rhododendrons and "Azaleas" is that Azaleas have leaves and buds on the stems between the main leaf whorls, while most other Rhododendron species don't. It's superficially a negligable difference, but it makes a huge difference in pruning practices.

My Father bought an azalea Blue Moon, two further azaleas and a Rhododendron back in the 70s which he had to grow in containers (his soil was a chalk/clay mix). Last year, when my Mother died, I couldn't bear to abandon them so they moved into my garden. They have survived the winter although one of the unidentified azaleas had to be moved out of a rain shadow created by a very tall conifer, and the Azalea Blue Moon put on a good show last month. The Rhododendron's leaves look a bit droopy but it has loads of flower buds on it. I am hoping it will put on as good a show as yours, Newshoots. None of these plants have ever been repotted but I would like to give them new pots, perhaps half-barrels like yours or ceramic pots rather than the dull, green plastic ones they are in. They have been in my garden a year now so I am hoping the timing will be ok. Let's hope we are both successful, Newshoots.

If the rhodos have been in the same compost all that time they really do need feeding Xela and if there are drooping leaves they need watering too.