Half barrel suggestions

Any suggestions as to what to plant in a half barrel, usually plant summer bedding in it but looking for something more permanent, barrel is about 3feet wide, looking for something that will stand a couple of feet, my location is on the north east coast so get plenty of cold easterly wind in winter, any help appreciated.

 

If it helps, my half-barrels, I think a similar size, have clematis, a Passion flower, and dianthus as permenant planting, with seasonal bedding as fill-ins at the front. Each year Lidl and Aldi do a fuschia standard, for around £6, so one of those goes in each barrel as a summer centrepiece. The barrels are against a wall (hence the climbers!) and the wall faces west north-west. The garden is a wind tunnel, so the plants get the wind side-on. I.e., they are blown along the wall, rather than flattened against the wall.

Being in Belgium, we are probably warmer than you, but our winters can be severe. A low of -10c is normal, not an exception, snow regularly lies for over a week, and we normally have a week or so where the daytime high does not reach up to freezing. And rain - oh yes, Belgian weather specialises in all sorts of rain!

 

Like @Sian in Belgium I have Clematis in mine and Tulips followed by Lilies. I didn't expect the Tulips to keep going for as long as they have but the good drainage large barrels give (plenty of stones/gravel etc in the bottom of the barrels) seems to suit them. The Lilies start into growth as the Tulips are finishing which help cover the dying Tulip foliage. I let the foliage die naturally so the bulbs have a chance to absorb enough goodness for the following year.
While perhaps not totally permanent both lots of bulbs have been in the barrels for 5 could be 6 years now. Apart from adding a lump of manure to the surface of the barrels during the winter they have had zero attention and just get on with it! My Lilies grew a "little" taller than I expected! I also grow some pretty foliage Heuchera in them. Fancy Heuchera won't tolerate my garden (drainage) but very happy in the tubs. I'm in Scotland so ditto @robbo re cold east wind