Johann Johannsson: The Theory of Everything (OST) (Back Lot Music)

Icelandic composer Johann Johansson's score for James Marsh’s film about the relationship between extraordinary astrophysicist Stephen Hawking and his first wife Jane couldn't be more different to the tough minimalism of his last effort, the acclaimed soundtrack for the 2013 film Prisoners. The mood here, on almost every one of the 27 short snippets, is lushly romantic, melodic and upbeat, taking its cues from the film's theme of the triumph of the mind and spirit, roaming through the cosmos while Hawking sits confined to a wheelchair by Motor Neurone Disease.

Film soundtracks work on two different levels. Johansson was paid to tackle the one about providing music to complement and augment action on the screen. And at that level this is a sterling effort, creating emotional thrust with massed symphonic ranks playing stirring melodies to polished perfection.

But the greatest soundtracks also stand alone as fantastic pieces of music without any need for a single image. Just listen to Ennio Morricone's masterful early soundtrack for the spaghetti Western For A Few Dollars More. And on that test, Johansson's latest is let down by over-emotional symphonic lushness.

On a lot of tracks you want to just shoot the string section. The best tracks are those where Johannson goes back to his compositional roots. 'Less is more' on the eerie darkness conjured by 'Collapsing Inwards' and the early section of 'A Game Of Croquet', very Philip Glass until the strings swoop in and mushify it.

The fast repeated piano motifs in the opening track, 'Cambridge 1963', also nod neatly towards Glass with a dash of Steve Reich – albeit too sweetly melodic to be either. Pared back moodiness also works in the solo cello on 'Camping', as well as the hesitant, reflective piano motif on 'A Model Of The Universe'.

Johannsson has come up with sweet melodies and clever spins on repeated motifs, of which 'Rowing' is the best. But while this works fine as a soundtrack to an emotionally-wrought film unfurling before your eyes, it fails too often to really engage as music on its own.