I agree it's a rhodo, not sure what to do now. Give it some light and air, feed it in the spring? I don't think you could expect buds if it's been stifled and sat on by too much ivy. Not sure when to prune it back - I think it depends how scrawny & drawn it is.

I'd leave it for a year and see if it forms flower bud, to see what variety you've got. If you do want to cut it back, do so in late spring, so that new growth can grow away without fer of frost damage. It may be the non-native (and somewhat invasive) ordinary purple flowered rhodo. ponticum. Phil J

I thought it looked a bit like ponticum, Phil, but I think there are other possibilities too.

I'll leave it in situ for now and see how it develops....I really won't give it space if it's the weedy variety. At the moment it isn't causing any problems and I'll see how my layout works once I've got it sorted. A reprieve til Spring I reckon. Thanks Phil and Beattie :)