Wow! It almost looks like a yellow Delphinium. I didn't know there was one but looked it up and there is. Delphinium luteum. Don't know if this is what yours is but it amazed me.

Aconitum lycoctonum?

Yes, aconitum as Bamboo says. AKA Wolfsbane, etc. Extremely poisonous according to all sources, even just by contact

I thought I'd posted a reply.
yes Bamboo that is what it is I had a sneaking suspicion it began with an l. I remember that I bought it at Burton Agnes several years ago.

I have tried to grow several Dicentra species of which one was a yellow flowered one so I was wondering if it was that but the leaf and flower form really did say aconitum.

I know they are very toxic Darren, thanks. It is one of the few plants that I wear gloves for when I am gardening.

Under no circumstances should you lick it either, definite no no😇

Our previous garden was full of Aconitums of every type. I like them. Never gardened in gloves and spent many hours removing the seed heads without any of the toxicity problems. Yes they are poisonous, but only if ingested. Brushing past them in the garden will not kill you.
Where is the Poisonous Gardener when you need him?

I never used to wear gloves, Owd, when dead heading them etc, but my daughters read about a sad and rare case of a young man who died after handling them. Think he was a gardener. they made me promise to wear gloves and as they bought me them I feel duty bound to wear them. Having said that I have cut flower stems for a vase.

If that was the case which was in some of the more lurid papers then when it was investigated it was found to be highly unlikely that the man in question was actually killed by just brushing past Aconitums

I'm here Owdboggy. Been a bit busy.

Yes Aconitums are highly toxic if eaten though I once met a couple who ate some leaves because they planted them amongst their salad plants to make the veg garden pretty. They survived after a very unpleasant forty-eight hours.

The story Seaburngirl refers to is typical of the way the press latch onto the lurid and then never let it go. The poor chap was taken ill and died about ten days later. He had none of the symptoms of Aconitum poisoning and the doctors investigated all sorts of possibilities before, finally, his father suggested looking at the plants in the garden where he worked.

The inquest recorded an open verdict with the coroner stating that there was no evidence to suggest he had been in contact with monkshood prior to becoming ill. This didn't stop the press from still saying it was the plant. And the interview I did for ITV that aired in the southern region didn't stop the false information either.

If you want the full story http://www.thepoisongarden.co.uk/blog2/blog081114.htm and http://www.thepoisongarden.co.uk/blog2/blog250615.htm

Short version - if you could die from contact with Aconitum there would be dead bodies in most gardens.

Thanks! I knew it was a fudge.