It's 1942. The Nazis have occupied France. The Battle of Britain is being fought in the skies over London. The British have been routed at Dunkirk... and two army dentists have decided to launch their very own private invasion of France.

Armed with two revolvers, 20 rounds of ammunition, and ten grenades, old veteran Sergeant King (Cranham) and his youthful protégé Private Cuthbertson (Bill) steal a fishing boat from the Cornish coast and sail across the Channel into France: "Open wide Adolf, the dentists are coming!"

Unbelievably, this bizarre tale of British eccentricity is based on a true story which screenwriter Richard Everett found while trawling through his local library.

Taking King and Cuthbertson's supreme folly as its starting point, "Two Men Went to War" follows the mismatched pair as they try to make their very own contribution to the Allied effort, blowing up a German radar station in a bumbling adventure that would make Captain Mainwaring proud.

There's no denying the cast and crew's good intentions, with Cranham's turn as the gruff old sergeant hilarious and Derek Jacobi lending some welcome weightiness as Churchill's intelligence officer.

The problem is that "Two Men Went to War" just doesn't have the mettle to turn this tale of British resourcefulness into a fully-fledged feature.

Despite its humour and obvious love of the kind of pluck that turned the tide in the war, this should never have been taken from where it really belonged - on the small screen sandwiched between a Dad's Army double bill.