Looking for an evergreen fruit tree

[Kelly Williams]

I’m looking for an evergreen fruit tree to accompany my 50 year old olive tree.
It will have to be happy in a large pot/container as we hit clay 2ft down. It will have full sun but be battered in the winter (I can cover for frost but we are heigh up and I can’t protect it from the wind)
I have been looking at a mature pomegranate tree, is it likely to survive in these conditions?
Thank you

[ameno]

Whether a pomegranate survives depends on how cold it gets where you are (which you haven't said), and also how wet the winters are.
Also, if you have 2ft of top soil before you hit clay then personally I'd recommend just planting it in the ground.

As for other recommendations, must it fruit most years, and must the fruit be edible? I mean, a pomegranate is very unlikely to fruit in this country, even if it's mild enough where you are for the tree itself.
Strawberry tree is a possibility. They fruit reliably as long as you don't get too cold in the winter (they bear their fruit through the winter), and they are nominally edible, although I can't say I'd recommend eating them.
Loquat is also a possibility. It's very unlikely to fruit in this country, but it has large, handsome evergreen leaves and grows well enough in this country (ny neighbour has one).
There's always cherry laurel. It's usually grown as a shrub, but it can be trained as a tree. The fruit are poisonous, though.

[nickdub]

I'd second the Loquat as a handsome tree I've grown some from seeds I brought back from Portugal one year - I haven't got round to planting any in my garden mostly because I've grown so many other trees over the years that there is very little room for another one left.

My other suggestion would be to have a good look at the citrus family, particularly in relation to the cold tolerance of different varieties. The range of citrus trees available is virtually infinite as they can be cross-pollinated to produce variants more or less at whim. Plus points for them are that, although I don't think you will find one that fruits reliably to give anything worth eating at least (if you do let me know please), the flowers are generally beautifully scented and the leaves have essential oils which can be used in a variety of ways including cooking.

[ameno]

On the subject of citrus, I considered recommending a yuzu. They are one of the hardiest of all citrus, and should survive outdoors in the south of the country once they are a few years old (young ones are more tender). They likely wouldn't like cold winds, though, and probably wouldn't survive outdoors up north.
If you really want a citrus, a trifoliate orange will survive outdoors pretty much anywhere in the country. I saw a large one in a botanical garden in Krakow last year (covering in unripe fruit, too), and it gets pretty cold there in the winter. However, they are deciduous, unfortunately. They also usually make more of an unruly bush, although they are large enough that they could be trained as a small tree.