I took this photo of a Speedwell flower yesterday (27 Sep) in a typical situation beside an (empty) field obviously used for crops. there were many plants all just a few inches high. It's probably Common Field Speedwell (Veronica persica) but the lower petals on all of them were very pale, almost white which looks a lot like Green Field Speedwell (Veronica agrestis) in my flower book. Is there enough in these photos to decide for definite?
I reckon its Veronica persica. That usually has pale lower petals. The calyx segments which you can see in the background in the first photo are quite pointed, they are much more bluntly rounded in agrestis.