Its a solanum. member of the potato family. nice climber too. you can prune it to keep it in its desired space.

Don't say you're not much of a gardener, its very pretty.

Is there a solanum that grows to twenty feet tall, without support?

I thought from first few pics that it was a Ceanothus. But the last pic is certainly solanum.
Is the flower you show actually from the tree? Not clambering through it?
Like Bulbaholic, I don't know that solanum will grow that big on its own.

Solanum can attain much larger heights, with support they can scramble much quicker to great heights however all the growth that is put on gives it its own framework to attain a great height as the growth matures, normally you can expect the bottom growth to be sparse, but with a little help you can take the top growth down and encourage it to green the base up or you could hard prune in the spring, long prolongued cold snaps like in recent years can completely kill off solanums the one in the picture looks like s, crispun

Thank you everyone: Another question :
This plant has been soo successful in my soil, I would like to take a cutting and try to grow it elsewhere? I am a novice gardener - at best - so would like some advice on how best to achieve this, i.e. when is the best time of year to take cuttings, should I buy some form of rooting compound, where should I make the cut e.t.c.??

The plant continues to flower even now(26/06), so it gives good value, and I would like it in other parts of my garden! Your help would be appreciated as always!

You can take semi ripe cuttings and round about now will be ok, possibly try and layer some too.