Sambucus nigra ‘Black Tower’ and ‘Golden Tower’ are slim, columnar elders which will grow to a height of 2.5m, spread 1.2m. If you want something evergreen, Griselinia littoralis can also be pruned into a columnar form and grows well in this area. You could also try Solanum crispum ‘Glasnevin’, a climber with blue flowers which becomes woody and shrub like as it gets established.
This is Griselinia grown as a narrow hedge which is only 1.5 feet deep, over 6 feet high. It gives a good backdrop for other plants and has a fibrous root system which should not compete aggressively with your roses. I also grow it as stand alone shrubs in loose or columnar form.
I'd just add Pyracantha to the list. Yes it's prickly but you can train it really tight into your fence so you won't lose much depth. You'll get flowers then colourful berries. And they grow fast.
But Ceanothus would still probably be my favourite. 'Concha' or 'Puget Blue'. I've seen the latter trained tight against a wall but I've never tried it myself. Unfortunately though they're relatively short-lived.
Clay soil - Cheshire/Derbyshire border. I play with plants and soil and sometimes it's successful
For your conditions I'd be tempted with a Fremontodendron it would look great there , evergreen as well . cotoneaster horizontals would grow up the side of the fence
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@ddd777 the border runs (in that part 4-5 ft)
@DaveGreig newbie question for you - can you explain what you mean by the angle on the cordon. Interesting idea..
But Ceanothus would still probably be my favourite. 'Concha' or 'Puget Blue'. I've seen the latter trained tight against a wall but I've never tried it myself. Unfortunately though they're relatively short-lived.
I play with plants and soil and sometimes it's successful