Plant ID

KeenOnGreen

Think this might be a Geranium, but don’t recognise it as anything I planted.  

Mary370

Are you sure that flower is part of the plant?   It looks very small in comparison to the leaf.   The leaf reminds me of chrysanthemum.

Alan Clark2 in Liverpool

The flower looks like a Silene, but the leaves do not.

KeenOnGreen

The flower is definitely from the same plant.  Perhaps they have not fully opened. They are only just opening.  

Dovefromabove

The leaves look to me like Creeping or Meadow Buttercup. 

The flower isn't a buttercup but not sure what it is ...  looks a bit like Corn Cockle (Lychnis githago/Agrostemma githago) .... it's rare in the wild nowadays  but sometimes included in some wild flower/meadow type seed mixes  ... did you sow anything like that last year?  ... it's early for it to be flowering too, but ... 

Have a look and see what you think ... 

https://www.pfaf.org/user/Plant.aspx?LatinName=Agrostemma+githago

Where's @nutcutlet?

Asarum

It is a geranium, or cranes’s bill, but I’m not sure which one.  

KeenOnGreen

The foliage doesn't look like Corncockle.  I do think it is some sort of Cranesbill, I'm sure Nutcutlet will solve the mystery soon.

Lyn

It’s a Cranes Bill geranium, I think misleading because it’s dropped some petals.  
Should be 5 pictures shows only 4. 

Borderline

KeenOnGreen, have a look at Geranium Molle or sometimes called Doves Foot Cranesbill. They can vary in colour tones, but are quite small too. I agree it is most likely to be a Cranesbill.

Dovefromabove

@Lyn    does the Cranesbill geranium have those elongated calyces behind the petals? It's not a feature I remember and they're not shown in the illustrations in my books.

Lyn

I think so.