IT may have sent some critics hurtling round the bend, but the BBC’s Glasgow to London train-set thriller Nightsleeper is proving a runaway success internationally. Producers Fremantle have sold the six-part series to 146 territories worldwide, including Australia, Denmark, France, the Netherlands, Portugal, Iceland, Japan, and New Zealand. The global sales follow ratings success at home. The first episode of the BBC One and BBC iPlayer series attracted 8.5 million viewers, making Nightsleeper one of the UK's most-watched dramas of the year.