Well, it is a scarlet pimpernel but it is not scarlet. This is a blue variety of
Anagallis arvensis, Both this and the brick-red variety are found in Andalucia but this was the most common where I have been. It is called
murajes in Spain (a name of unknown origin also used of chickweed,
Stellaria media, which has similar leaves). The Basque name is
amorrubedarr, meaning "rabies herb".
There is another blue pimpernel in Spain,
A. monelli, but that has thin, long leaves and larger flowers. That one goes by the glorious Spanish name of
Centaurea real, the Royal Centaury,