Differentiating between violets
The family of violas can be hard to tell apart, but there’s a great ID guide published on Twitter.
I’ve had quite a lot of trouble sorting them out as you can tell from viola blog posts of early 2020.
The violas I have spotted have been growing in open ground such as short verges.

Sweet violet – Viola odorata

Identified by rich purple (or white) flower colour with rounded sepal appendages, perfume, and course round leaves.

Common dog violet
More delicate and pointed foliage, paler, bluer flower, large pointed sepal appendages, dark veining on bottom petal, paler spur.

There are of course other violas that I haven’t yet spotted or confidently identified!
Blog posts mentioning Violas or violets are tagged Violet
http://photographingwildflowers.co.uk/tag/violet/