Potty British comedy packing them in

Saving Grace, a British comedy about the adventures of a marijuana-growing widow, is quietly becoming an international blockbuster.

Last week, the film's average takings were more than X-Men, What Lies Below and Hollow Man, distributor PrimeEnt said.

Two-time Oscar nominee Brenda Blethyn stars as Grace Trevethen, who finds herself deep in debt and saddled with a mansion on the Cornish coast of England after the death of her husband.

When Grace nurses her gardener's ailing cannabis plant back to life in her huge greenhouse, she realises how to turn round her fortunes.

Among the scenes is one with two elderly shopkeepers who end up munching breakfast cereal after brewing "herbal" tea all day.