Where rock music is concerned, the English Channel is wider than the Atlantic. The gulf is embodied by Johnny Hallyday, a legend in France who has never taken off in Britain. British music lovers are more likely to buy an album sung in French by a Malian act such as Amadou & Mariam than one made by a Frenchman.
On the dancefloor, national differences melt away, and French acts including Daft Punk and Air have made a name overseas. But it's hard to think of an equivalent among singer-songwriters. If anyone can bridge this great divide, it is Charlotte Gainsbourg. Her father, Serge Gainsbourg, was the most French of all rock stars and a maverick; her mother, Jane Birkin, is an English actress and singer who had already gone native in Paris when she gave birth to Charlotte in 1971. Jane and Serge's best-selling duet, the lovably cheesy chart-topper Je T'Aime (Moi Non Plus), had come two years earlier.
In France, Charlotte is a junior national treasure who has made 35 films and a No 1 album (5:55, from 2006). In Britain, she is an arthouse actress who also does a bit of singing. That could change with her recent album, produced and largely written by Beck, the fitfully brilliant Californian singer-songwriter.
As the daughter of a famous duo, Gainsbourg should know what she is getting into. At 39, Beck has one foot still in art school and the other firmly in the mainstream.
But he also has a powerful signature - ramshackle rhythms, crunchy noises, IRM is an album of thirds. Four or five songs are typical Beck productions with a breathy French vocal attached; another four or five are Charlotte Gainsbourg tracks with little trace of Beck; and only two or three feel like real collaborations.
The title sums up the problem. IRM is the French for MRI, as in the scan - one song reflects on the brain haemorrhage that Gainsbourg suffered in 2007. But merely switching two letters is enough to leave the phrase lost in translation.
If you don't care whether a record hangs together, there is plenty to enjoy. Heaven Can Wait is a Beck bullseye, a frayed pop song with a stomping rhythm and an effortless melody. Le Chat Du Caf is a well-crafted electronic ballad, as French as pain au chocolat. Dandelion is toe-tapping two-string blues, as American as a pair of jeans. On Voyage, both traditions are left behind, with a gutsy African rhythm, dramatic film score strings, and a vocal that is bilingual and less wispy. But taken as a whole, IRM doesn't bridge the great divide - it reinforces it.