I found out once but!! I've forgotten. its a late summer flowering plant.
The tallest plant is a type of Begonia. Probably quite tender.The front low mounds look like a mixture of of Heucheras. No idea what the top left clumps are.
Begonia, that could be it. We bought it at a NGS garden a coupl of years ago, the lady said we wouldn't find it in any garden centre. Thank you.
Some Begonias are really rare and special. I like these ones too, but could never plant it out. Try Dibleys Nurseries, you may be able to find it there.
Top left: beetroot.