There were many butterflies on the thistles along our lane, the most prolific being the Green-veined Whites which are often mistaken for the Small Whites.  They are common among damp grassland and woodland and have white wings with prominent greenish veins on the back and conspicuous white tips on its antennae.  Like this one, those in Scotland tend to have a yellowish tinge on its underwings although it is not obvious in my photo.