Caesalpinia Gilliesii, comeback.

Looking good @pete. I don't have the space yet to plant out, maybe next year when bigger.
I will have a sunny site available then but not much shelter from the rain.

 

I think something behind it rather than free standing could be the answer.
Reflected heat must help and as long as well drained it should do well, as I think I said earlier they seem to like poor soil.
So go easy on the manure.

 

They certainly flower a lot better in sandy-ish or stony soil. Not had a problem here with hardiness. Planted near a wall they've survived -12°C albeit for brief periods.