Ask Alys Fowler: should I make space for my strawberry tree?

Our gardening expert has the answerWe planted a strawberry tree (Arbutus unedo) in our small garden seven years ago. It is now just over 2m x 2m, and is touching a birch tree on the north side, and a smaller pittosporum to the south. Should we consider getting rid of the pittosporum, and hope to train the tree southwards?
Arbutus are very easy to prune and respond well to being clipped; I regularly give mine a haircut. I find crown-lifting the canopy to get more light underneath p