Magnolia grandiflora would suit the conditions and aspect as would one of the many camellia species, mature height may be a consideration with these.

I agree with Dgw magnolia grandiflora is magnificent, it depends when you also want it to flower.

I suspect that most of Scotland would get too cold for Magnolia grandiflora, though. On the west coast, maybe, if out of the wind. Maybe some of the larger varieties of Ilex, instead?

How big an area will you be able to give the tree or shrub. What is the height and spread you are aiming for ?

I'd go for an Amelanchier - not evergreen, but that's the only drawback. Usually makes a multi stemmed shrub or small tree, has blossom in spring, leaves which turn red in autumn, and berries. Depending how big you want it to be, there's Amelanchier 'Ballerina', around 13 feet, Amelanchier lamarckii, taller, more small tree like, and a new one, Amelanchier 'Obelisk', a smaller variety.

I have Amelanchier canadensis in my garden in Scotland. Clay soil and in south/SW aspect. Lovely specimen shrub/tree. White flowers followed with red leaves in autumn, though not evergreen. Holly is also something that you should look into as well as Mugo Pine. That stays pretty small and can be pruned after a number of years.

Scotsgran - i have two areas i could use, one area is more shady and i could have something around 5 feet, borders maybe 3 feet wide. Other area is sunny but nearer front door border same width but would prob want a shrub thats colourful but only a few feet in height, off to google the suggestions

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There are lots of good suggestions there. In the shadier area you could also try a camellia. Grow it as a standard ie with a tree like trunk. You could choose a variety to give you winter flowers from Jan - May depending on your choice. Near the door something like Euonymus japonicus Aureopictus will give a brightly coloured shrub which can be pruned to keep it to the size you want.