It is the eternal question for an artist of Paul McCartney’s stature: what next? What next when you have… well, that list of achievements, with even the long-touted standards album now ticked off with last year’s ‘Kisses On The Bottom’, hardly needs re-iterating. On one level, you might reasonably think that in terms of awards, honours, sales figures, shows and even artistically there is nothing left for him to strive for. But on another, there is always the search for the next truly great song, for the next unexpected challenge. For the new.