Was there ever so much hype about a new ballet as there has been about Sir Paul McCartney's Ocean's Kingdom? Not in recent years at any rate, and no doubt that's exactly what the New York City Ballet were banking on when they asked the former Beatle to write them a new stage work. However, the resultant musical product should be viewed as a salutary lesson in what happens when you commission above a composer's skill-set.

McCartney is a master tunesmith, but his strengths lie in small-scale form. Even his previous larger classical works have either been split into numerous short movements, or else been choral works where the texts have provided a clear structural framework. In asking him to compose almost an hour's worth of purely orchestral music – a symphony in other words, given the resultant work's four movements – the NYB were asking him to make a massive leap in terms of melodic development and large-scale structuring. Unfortunately for everyone, he simply doesn’t have the classical know-how to pull it off.

The first movement is a painful study in staticity, built around a three-note motive that moves precisely nowhere. Changes in dynamic, and the odd variation-style embellishment, just don't cut the developmental mustard over 14 long minutes. Sure, it sounds like the sea in terms of its rolling, undulating feel and the expansive scoring. However, the overall impression never rises beyond that of a poor man's version of Debussy's La Mer. With the second movement, Hall of Dance, there's an increase in melodic interest and a tightening of structure, but even so the overall effect is still one of musical doggy paddle. As for the music itself, it feels highly borrowed; amidst the mélange of underwhelming pastiches, from neo-classical Russian to Copland, and pretty much everything else in-between, it's hard to get a handle on what McCartney's own orchestral musical language might be.

The area in which McCartney does excel is in his choice of collaborators. Andrew Cottee's evocative orchestrations, John Wilson's skilful arranging and conducting, and the London Classical Orchestra's performance, make the best of a bad musical situation. Even so, there's a brief moment during the fourth movement, as a Copland-like theme hammers grimly on, when the orchestra appears to be wondering along with the listener whether they can make it as far as the finishing line.

McCartney makes much of his approach to classical composition being "driven by his heart rather than his head, and inspired by feeling rather than specific technical knowledge". Trouble is, there's no getting away from the fact that in large-scale orchestral composition you really do need the head bit as well. If Ocean's Kingdom were a fish, it would be a flounder.