Looking for a feature plant

The plain green Phormiums are the hardiest but they can get too big for a confined space. I grew one here in the ground in an exposed position and it never looked particularly healthy with yellowing leaves, brown spots and brown tips. My climate is milder down here than where you are @fairygirl and all my variegated Phormiums have made it through the last 10 winters with only the odd brown leaf to remove. You may have milder winters where you are @fumanchu. If not, it may be better to avoid Phormiums and perhaps try an ornamental grass like Calamagrostis Karl Foerster (H5, down to -15C) or Panicum Northwind (H6, down to -20C) which are both columnar and also give winter interest.

 

These are the two grasses I mentioned @fumanchu, there are two Calamagrostis here with flowering stems and the Panicum in the foreground not yet flowering.

 

Although Jedburgh is in the Borders, it's actually not that much further south than where I am - it's farther east though. The border at the far east side is much further north than people often realise. When maps of the UK get shown - they're often not truly accurate in terms of north and south either, because the whole island looks nicer if it's 'vertical'. It's also why people think Lands End is the most westerly part of the mainland, when it isn't.
The winters can be colder there in terms of frost/ice/snow, especially in an exposed site, which is what this seems to be. Exposed sites shred foliage very easily.

Wet cold is far more of a problem for Phormiums, but if temps don't decrease more slowly and gradually over winter, that's where the real problem lies, and that's what we've been getting here in recent years. Higher autumn temps, then a sudden drop every so often. The cold temps in isolation aren't the issue - it's the abnormally higher temps preceding them that causes the problem, especially in heavier, wetter soil, and after prolonged wet weather.
We've always had regular spells here of well below minus 6s, 7s and 8s, and beyond, which is fine if the drainage is sharp, but if the previous day was plus 6 ,7 or 8, and then there's a swing back down to minus 6, 7 or 8 etc, and is being repeated, that's where the problem with fleshier plants occurs.

 

Araucaria araucana, monkey puzzle, is hardy, don't know where you're looking your info up, but make sure it's not an american site as they haven't got a clue about the UK!(or anything in general come to think of it!)
If you've got loads of money to spend, wollemia nobilis..the wollemi pine would make a statement, as would arbutus unedo, strawberry tree...smallish and cheaper.
If you're very cheap like me, leycesteria formosa will give a little bit of interest and stay under 5ft and won't break the bank

 

I wonder if @fumanchu was looking Norfolk island pine, Araucaria heterophylla often grown as a house plant.

 

You could even try a box, (Buxus), ball if you dont mind clipping it once a year.

 

Are you looking specifically for a tree?
I have some Dieramas, Angel's Fishing Rods in the garden which make good clumps, the flower stems grow to about 4/5ft, wafty, perennial, spiky.