Can you identify this British comedy for me? It was a film from at least ten years ago.

A middle-aged, middle-class British housewife, in her twin set and pearls, is left with no money after her husband commits suicide.
With the help of a local teen-aged layabout in her quaint English village, she starts growing large amounts of marijuana in her greenhouse.

The entire village, including the local bobby, assists in the conspiracy. One scene shows the villagers seated in folding chairs in the middle of the high street in order to enjoy the second-hand smoke.

There are some London gangsters who buy the pot.