We have a 10m x 5m estate type back garden in Hampshire.

We want to plant a couple of feature trees, like silver birch.

The criteria a

slim, upright habit,
5m max height
white or whitish bark

Any ideas please?

The Swedish or Cutleaved birch is more suitable as it is less vigorous than our homegrown forms. It is a gentle and very pretty tree, growing to around 15 feet, with a delicate canopy that moves in the slightest breeze.. You could contrast it with the Himalayan birch, large leaved and brilliant white trunk.