'Cabbage Whites' (Large and Small Whites) are 'countrside' butterflies. Their main natural foodplant are wild members of the cabbage family (surprise, surprise) and historically would have fed principally on 'Garlic Mustard' (Jack-by-the-hedge). There are a LOT of wild brassica (crucifers) in the wild UK flora.

Unfortunately they have found that cultivated cabbages are more to their liking, and occur in much higher numbers and closer density to the wild food, so I guess its no surprise the little blighters have changed their habits.

Nature is wonderful (sometimes......)

LCG