This is the view from our bedroom window. I have 46cm wooden barrel containers either side of the log store. The one of the right has a Photinia serratifolia (pink crispy) which is meant to grow to max 1.75m tall and 1m wide. I want something of a similar size for the other planter.

It must be evergreen to provide a nice view all year round, and also compliment the Photinia. Ideally something flowering, which won't drop too much on the slate. I can switch the planters around if necessary (i.e. put the Photinia on the left).

I was thinking of perhaps an upright rhododendron but they mostly seem to have a larger spread than height.

Any ideas? (I'm in the UK)

Thanks :)