One to guess!! ?

[Paul S]

Broadly, yes. Berberidaceae next step.

[Chad]

Damn, I thought I had excluded them.

So far I've checked;

A double Thalictrum, but there isn't a white one.

Anemonopsis, for that inner ring thing.

Epimedium, but I can't find one with incurved petals, and that led to Berberis/Mahonia, but it is a very open panicle and off white flowers.

I had a quick scan through the rest of the family and hadn't found anything.

I will double down on that family!

Chad

[Paul S]

Getting warmer...

[Chad]

Is the fact the flowers are pale, even pallid, of taxonomic significance?

[Chad]

And now I'm lost.

When did Mahonia get absorbed into Berberis?

I suggest a specific of either pallida or hartwegii and chose your own genus!

I didn't know either of them, this has been fun.

Chad

[Paul S]

Mahonia russellii

[Chad]

Tell us more; a tender Mexican?

[Paul S]

Mexican, yes. Rare, certainly, but i don't think tender. Mine is several years old. Roy lancaster grows it and waxes lyrical. This was one of Mark Fillan's lines at one point. For my money this is the best mahonia, leaves are soft and have the most amazing texture en-masse.

[Chad]

Is it scented?

Have you another poser for us?

Chad

[Paul S]

Not scented that I have noticed.

Nothing desperately unusual or tricky to ID, I don't suppose. Surprisingly, I have a very busy weekend but I'll have a closer look around the garden nex week.