Loach draws naturalistic, committed performances from his actors

Encountering American activist Sam (Adrien Brody) during one of his guerrilla-style stunts to raise awareness for the janitors' plight, Maya encourages her co-workers to unionise.

But her involvement in the campaign has a profound impact on her family, friends and community.

Transplanting Loach to sun-drenched California has not diluted his righteous indignation, and there is clearly no danger of him being seduced by the blandishments of Tinseltown.

The soppy romantic subplot and overly neat resolution suggest some concessions have been made to augment the film's marketability.

But this in no way detracts from the compelling human drama of Paul Laverty's script, which roundly castigates corporate America for its heartless and cynical exploitation of the country's most vulnerable minorities.

Loach always draws naturalistic, fiercely committed performances from his actors, and Bread and Roses is no exception.

Padilla is a real find, although it is Carrillo who impresses the most as embittered wife and mother Rosa.

And readers anticipating a didactic slice of agitprop can relax.

Bread and Roses is not without humour, most notably in the scene where the janitors gatecrash a Hollywood party attended by Tim Roth, Benicio Del Toro and a host of other Hollywood notables.

Bread and Roses is in UK cinemas from 27 April.