Plant in need of ID

in Plants
I was telling Nut yesterday about this plant that has appeared in the garden - it appeared last year and possibly the year before, but in an area which was meant to be lawn, so got mowed.
This year the lawn is no longer there, it's now the little wilderness behind the new pond and the plant has appeared again.
Feathery carrot-like foliage but softer, and growth like an umbellifer but not one I recognise - round stem. We've marshes nearby so I did wonder about Water Dropwort, but I think the leaves are too finely divided for that.
The gardener-before-last at this address seems to have been a 'proper gardener' so it might be an interesting cultivated plant - or it might be from wild bird seed - or ............... anyone got any ideas?
“I am not lost, for I know where I am. But however, where I am may be lost.” Winnie the Pooh
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Good morning Dove. I can't remember if we discussed smell to the leaves. If we did I've forgotten the answer
..something rather carrot like about it..lol.... regardless..I think your little pond is lovely..charming...with those rocks and pebbles, and other features...looks very nature friendly...
Thanks Salino
Nut, I don't think we did - I've just been and picked a leaf and had a good sniff - nothing other than a very faint cow-parsley type smell.
Are the leaves like a fools parsley (aethusa cynapium)?
I don't know the plant, I was just flicking through my weed book...
I've looked at Fool's parsley online and in my Keble Martin - doesn't look quite right - I've taken a close up of a leaf - what do you think?
Although the main stem is cylindrical, the leaf stems have the groove on the upper surface like Cow parsley.
Sorry, it's a bit dark - I didn't use flash in case the white paper flared. If you want one with flash let me know.
I know it won't be, but leaves remind me of some types of parsley and stalk a bit fennel like
What about Salino's suggestion? Wild carrot? Or was that where the stems were different?
I love a good weed mystery. I've got a few I'm cultivating at the mo just to see what they turn into...I know I could ask you guys and find out in a second but it's also fun to watch them...isn't it??

Is it Hemlock? The leaf looks very similar.
They look similar but not the same to me , they seem more finely divided and and there's no mauve blotches on the stems
you're right Dove hemlock and wild carrot are more finely divided as well as those red blotches on the hemlock stems.
The leaves look quire shiny compare to some.
It's not necessarily a weed. Other umbellifers have become quite 'in'. Ammi etc
not suggesting that's what it is, I don't think it is.