What shrub is this?

Hello
My son has been doing work experience at a retired botanic garden in Wiltshire. This beautiful flowering shrub is thriving in this week’s warm weather but nobody seems to be able to identify it. Any suggestions as to what it is? thank you

 

Google lens says it's Berberis valdiviana. But the foliage doesn't look as shiny as Berberis - also not sure of the scale - a hand in shot would help please!
It looks great though.

 

I agree with @CarolineL foliage is not right for B valdivana I have that in my garden.
A couple of questions roughly how tall is the shrub and are there any spines on it?

 

It’s easily 4m tall but it has been untended for some years and left to do its own thing. I’ve taken a better photo of the tiny flowers and leaves and a shot with a hand so you can get an idea of size! And no spikes or spines on it at all as far as I can see Thank you

 

Original image enlarged.




Berberis valdiviana looks good to me.
Pics from our old garden in April

Berberis valdiviana - Trees and Shrubs Online

Quote from link above.
A sturdy evergreen shrub 8 to 12 ft high; shoots glabrous, formidably armed with stiff, three-pronged spines 1 to 11⁄2 in. long, but sometimes quite unarmed; spines grooved on the lower side. Leaves 3⁄4 to 3 in. long, 1⁄2 to 11⁄2 in. wide, oval to oval-oblong, the base cuneate to rounded, the apex abruptly narrowed to a mucro, varying from sparsely spiny-toothed to entire, glabrous, glossy; stalk 1⁄4 in. or less long. Flowers saffron yellow, 3⁄16 in. wide, borne twenty to thirty together densely on glabrous, pendulous racemes 1 to 11⁄2 in. long. Fruit roundish ovoid, 3⁄16 in. long, purple, bloomy; stigma very prominent. Bot. Mag., n.s., t. 139.

These leaves are from a different garden ..NT. at Threave in Dumfries and galloway and look different...read above to explain.