proof that we do have trees in orkney even if we dont have a lot

Nice tree.

Are they self-seeded or deliberately planted ?
One looks like a silver birch, am I right,
and what is the other?

these treees were here b4 i got the garden. one is a sycamore the other as you say is a silver birch. i assume they were planted as the sycamore is on the boundary of mine and nieghbours garden. the silver birch must have been plannted as there are no others in the area

sorry checked today is not silver birch its a mountain ash (rowan) though the bark looks very silvey

That makes sense, both trees seem to be able to self seed in a wide range of conditions.