Hi burnley,
Not sure how small your small garden is but one tree that imediately sprang to mind was a Robinia psudocacia, if you choose the variety ' Frisia' which is a lovely yellow leaved form that looks brilliant at this time of year!
It can reach about 25ft but can be kept smaller if carefully pruned from a young tree.
Otherwise, how about an ornamental form of Rowan, one that is exellent for a small garden is Sorbus aucuparia 'hostii' that only gets to 10-12 ft. Good Luck. Tbird+