Thanks guys
For them's that wants to know, here's how I did the 'wire and seafoam' trees.
Get some lengths of stiff wire (find a flower arranger) and twist together
Twist the wire into several bundles and keep splitting the bundles as you twist, until you end up with a tree-like object
Cover the wire tree in 'Artex' - a paint/grit mixture used by decorators - or 'flexi-bark'
Take a seafoam tree (Forest in a box, Forest in a flash, or the Noch seafoam tree pack) and pull off the branches.
NB - For some of the trees I did, I just shoved a cocktail stick up the seafoam trunk (ouch!), glued it in with superglue, and covered the stick with flexi bark
I then attached the seafoam branches to the wire former with superglue and sprayed it with matt earth brown and olive green.
This is where I stop for winter trees, but you can make a summer tree by spraying spray glue on the branches and sprinkling on suitable flocks
Jon