A quick update and some questions.

Thanks Armandii, unfortunately I can't cut the hedge without removing the greenhouse. There is a metal mesh fence right behind the greenhouse and the hedge is growing through it .

Euonymous is looking like a really good option, it's even pretty which I thought would be pushing the brief too far. Slow growing is fine Kristen, I don't really need it to be a proper hedge, more a couple of plants to hide a fence and provide a wildlife refuge. Yes it is rather shady, but does get a bit of sun.

 

If you keep a strip clear around the bottom of the hedge (a couple of feet wide at least), mulch it well, and irrigate when dry (I recommend a leaky hose so you can give the plants a good soaking each time you irrigate them) then it will put on maximum growth. 3 years should see a decent looking hedge, and 5 years something that looks like its been there forever