Another London documentary at the tail end of the Olympic year, The Road has a promising idea at its core. Marc Isaacs takes us into the lives of people who have come to London from afar, settled along the A5, and struggled to make the city their home. They include the nearly blind, 95-year-old Peggy; Irish Billy, who lives his life between the pub pint and the kitchen vodka bottle; the hotel porter from Kashmir who describes intense, crushing loneliness through a learned bellboy smile; and the German ex-stewardess who still lives with her ex-husband.

There are a few wonderful moments, such as when Peggy rails against her late husband with humour, then anger, then sadness, and when Iqbal finishes his Skype call to his wife, then stares at his phone's empty screen. But the individual narratives often bump and clash awkwardly, and the voice of the director is a dominant, often patronising presence. It's there from the beginning, overwhelming young Irish woman Keelta's journey down the A5 from Holyhead, or in an incredibly painful scene in Billy's squalid flat. All too often, tragic tableaux feel like the film's priority, rather than the dignity of its subjects.

Wafty, philosophical voiceovers about leaving and arriving also feel trite, even though they roll over gorgeous, night-time shots of Maida Vale and Kilburn. You sense that The Road has a mission: to get its viewers to consider the lives of people many pass, every day, on similar streets. It succeeds in part. Nevertheless, there is a much better film lurking in these raw, rich materials.