I need a screen

Eucalyptus is evergreen and delicate, also rapid growing. Ceanothus is also evergreen, darker in colour, and more of a shrub, but makes a decent hedge. This also flowers blue in May which adds interest.

If the soil is damp, how about birch trees? They grow in clumps (say a group of five) rather than from a single trunk. The bark peels and has incredible character. They grow rapidly. The Tate Modern planted then about five years ago. I remember them being small clumps. Today, they look like a forest.

It depends how much planting room you have. Bamboos in clumps are attractive and evergreen, with the lovely sound when the wind passes through. Or a post and rope frame could be put in, with roses, clematis etc planted on it, with spring bulbs underneath. Some climbing/rambling roses are evergreen or almost. It does depend on how much light the site gets and what type of soil it is.

Laurel makes a cracking thick hedge that is good at absorbing noise. The dark green also makes a good background for flowering plants. Also consider Aucuba japonica (spotted laurel). Viburnum x bodnantense (sp?) flowers all winter (pink pom-poms) and produces lovely scent. All depends on space, of course. If your sister does not like her new neighbours, what about Cupressocyparis x leylandii...? te he... ;-)

Eucalyptus meets your requirments, however be carefull where you plant it has they have equally fast growing roots, which are also shallow and they WILL cause damage to hard surfaces if they are planted too close.

Don't be so ridgemental with the "evergreen" thing, Silver birch for example are just as equally beautiful with their leaves has they are without them.

Take care,

Scott