Yours does look similar to the photo of Viola cornuta Sue, but it is a much more rounded shape with blotches on the top petals where that has all dark top petals. It will be a hybrid of that one for sure.
Put the photos side by side and you will see what I mean. Then put yours next to the photo of Viola cornuta Skippy Frosted Face and see how they compare, the photo on garden world images shows a flower a little bent over and a little over exposed but they have the same characteristics. There is always variation but the general appearance is the same, even in your photo looking at the bottom flower it's paler.
If you don't think it fits any named variety in particular you could put it in Viola cornuta, if we come across a named one which really is a good match later it could be moved.
I vaguely remember these with the blotches on the wings, I used to look a lot at catalogues pre-internet days but there's so many new varieties that come on the market it's almost impossible to keep up with them! I have many small ones setting around which look to have crossed with the wild Viola tricolor and others I have grown in the past, now I just wait to see what sets around! I see some on the market which have been given names but look so much like my own crosses!
