Thanks, jono. I've studied music and I really dislike this clue. The real definition is 'suddenly', which is not the same as 'quickly' at all (e.g. 'presto, et al) imho. But, I can see how it might pass muster here given the degree of dubious clueing that's acceptable.
Oh well, just my two 'cents' worth. I dare not even ask about 2,5... I somehow feel certain it will put me off Paul forever.