It is indeed - they are the commonest of the 'blue' butterflies in urban gardens. Their first showing is in April-May when they emerge from their overwintering pupal stage with another showing in July-August when their progeny emerge. This second generation overwinters to kick things off again next year. The spring brood larvae usually feed on Holy whereas the summer brood are more usually found on Ivy - though a smattering of other plants are recorded as fodder.
That was quick! Many thanks. There is a lot of ivy around here - so presumably this was the result of a late summer caterpillar - but it may have to fly a couple of hundred metres to find a holly tree, which are just starting to flower now.