What is this pretty thing please?

It's arrived in my border uninvited and has just produced a spike of yellow flowers. Grey-green, deeply divided leaves, a bit dewy in the photos. Clump is about a foot across and six inches high. I have a feeling I've seen something similar growing in the odd front garden round here. Apologies for the somewhat blurry second photo!

 

Yellow corydalis, but I think they might have changed the name recently

 

Brilliant - yes that's it - thank you @Zigs! I'll hang on to it, might move it in the spring.

 

Just looked it up, it was only the Latin name they changed

Pseudofumaria lutea - Wikipedia

 

AKA rock fumewort I see - I think yellow corydalis sounds nicer!

 

It'll colonise walls, but the roots are nothing to worry about.

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Fumaria officinalis - Wikipedia

 

You're right, @Clare G, it is a pretty thing. What a lovely surprise!