88V8 wrote:I would beware of planting too many different trees. Sticking to a few varieties will have a unifying effect, whereas one of these one of those will create a visual dottiness. But trees of any sort are a wonderful asset to civilised living.
Coming late to this but +1 on both these points.
I must admit a hawthorn was one of my first thoughts - I know a house with an old one and it's a lovely thing. It's been pruned over the years so that there's not really any leaf below about 7', and I guess "ability to be formed into a standard" is probably a consideration for the kind of standalone use you're thinking of. But once you're there, you can have almost anything - I know a front garden which is just lawn and "lollipop" roses about 5' high, which looks amazing but is presumably a lot of work to maintain.
But I do like amelanchiers, which are a favourite of supermarkets as messy bushes - as plants they're quite tough and have pretty white flowers in spring. However they also work really well as standard trees - I know one that was planted (in rather shady conditions in heavy clay) about 12 years ago that is now about 15' high, but it's maybe half that width, it's tall and thin so might suit streetside, and the small leaves and twiggy tendency makes them quite "light" visually.
Rowans can work, but I'd extend my search to the rest of the genus - there's several native
Sorbus, and a range of foreign ones, so you should be able to find one of the right shape to suit. Wild service trees
S. torminalis have oodles of folklore associated with them and are good wildlife trees, but I'd guess are too big for you.
Fresh cobnuts are a thing of joy that everyone should have, the wildlife benefit is incidental - but like most hazels their instinct is to be a bit scrappy, they need pruning when young to get their shape going in the right direction.
I'm a huge believer in planting heritage fruit trees wherever possible, but recognise the problems in a shared space. One option is to have fruit desirable enough that they won't go to waste - I'm thinking figs. Interesting trees, but your soil is probably too good for them - they thrive on the North Downs where people are taking a pickaxe to bare chalk...
Another option might be a bay tree - it'd be nice to have a communal resource of bay leaves as they don't really work hard enough to justify their inclusion in the average suburban garden on visual grounds, although growing up we had one as a hedge against the wall screening the dustbins.
Also on an evergreen note, don't rule out some of the firs, which I've got a bit of a soft spot for and there's every shape and size. One could also serve as a communal "Christmas tree"....
Combining some of the above, maybe
Arbutus, the strawberry tree?
And for pure autumn colour - liquidambar?