Confidence: It's likely to be this, but I can't be certain.
Notes: Leaves and flower colour seem to suit this species though looking down onto the flower as shown in your photo doesn't allow for a more positive identification. Did you get any side on views? that may show the long pedicels of Slender Speedwell. Also Germander Speedwell is rather hairy, with two rows of hairs that run along the stem. Again a feature not visible in your pic.