mystery shrub

I have a shrub growing in my garden I would like identified. It is very spiney with very small burgundy leaves at present, although they might grow bigger as the season wears on. The spines also apppear to be the same colour a s the leaves. When I cut a bough I was amazed how the cut appeared, it was a very brilliant shade of Yellow.

islayhawk

 

Sounds like Berberis

 

Mahonia also has brilliant yellow coloured wood.
I think Mahonia and Berberis are closely related, and in fact there is a hybrid of the two.

 

There is indeed a cross, Mahoberberis 'Dart's Treasure but the description of small burgundy leaves at present makes Berberis more likely.