Norfolk,
United Kingdom 
Is this a wild or cultivated Geranium? This is growing in a pot which somewhere underneath all this foliage, is a Pelagonium. Was this something that just grew, or did I plant it and forget?
Meant to add that the flowers measure approx. 2.5 - 3 cm across, so are not Herb Robert size.
7 May, 2020
Answers
Definitely a true Geranium, not a Pelargonium, though I don't know which one. I'm curious to see which one, though they are't good doers where I live.
7 May, 2020
Love hardy geraniums. As Tug says they are good doers and not attractive to slugs either. Bees love some of them so I hope you are lucky in that respect. G mourning widow are one of the phaems and do attract insects and are very like yours but darker and taller.
9 May, 2020
Yep, from what I hear, hardy Geraniums are easy--sometimes too easy--anywhere that isn't flaming hot 8 months out of the year, like where I live. Ah, well.
9 May, 2020
That's interesting Merlin, I don't remember planting this, but it's in a pot rather than randomly growing in the garden, so perhaps it's just a memory blip. It's pretty and full of flowers to come so I shall investigate later to see if it's one plant taking up the whole big pot, with a top measuring about 18".
10 May, 2020
It's also interesting Tug that the plants us gardeners want to grow are the ones that don't like our soil or climate.
10 May, 2020
It looks like the real deal to me. Similar flowers to Geranium phaem but mine grow on tall stems. Nice colour too. Someone will know.
7 May, 2020