Gerald Roth discovers that his old Longines wristwatch, left to him by his dad as a relic of the turbulent 1930s, is not just a collectable rarity but also worth an absolute mint of money. He only learns this when he sends it for cleaning and discovers that if he put it up for auction at Sothebys all his money troubles would be over.
Of course theres a snag: what makes it valuable are the initials JvR, a swastika and the numerals 1930 engraved inside the case. This suggests the watch was first owned by Hitler's Foreign Minister, Joachim von Ribbentrop. And among the closet present-day Nazi collectors of Third Reich memorabilia many, it seems, in high office the price could go as high as £40,000 for such a prize.
But Roth is a Jewish wine merchant and when the facts emerge at a family Passover dinner, there is outrage that he could ever consider enriching himself with blood money and as a means to rescue his ailing business.
Oddly enough the bare facts of this plot device are not fiction. Co-author Laurence Marks actually owned the watch in question, bought in LA in 1985 without knowing its provenance. When the truth became apparent he and Maurice Gran saw the opportunity to write a play that would link the watch to a wide-ranging family debate about Jewish identity in the multi-cultural Babel of present-day Britain.
It was an idea which appealed to the Controller of Radio Four who commissioned an Afternoon Play, aired with great success two years ago. Thus inspired, the writers had even introduced a speaking role for Ribbentrop himself, the first Nazi to be hanged at Nuremberg, who makes a spectral appearance to clarify matters for latterday audiences who otherwise may not have grasped all the facts needed to consider the dilemma facing Roth.
But Marks and Gran owe their joint reputation for success in writing television sitcoms, which also gives their full-length theatre version of the plot more space to introduce a string of Jewish jokes to keep us chuckling throughout the two hour Passover night discussions. And when a fight between brothers results in a mass of broken wine glasses on the dining room floor, the mood is still light enough for a comic aside about Kristallnacht.
Christopher Woodeson gives a well-focused performance as the pragmatic Roth, whose common sense tells him to sell the watch and bring financial benefit to his family circle. Meanwhile his brother David, a taxi driver played by Andrew Paul, raises his fists against such two-faced wickedness but still leaving the family gathering at a key moment to collect a valued Saudi client from Heathrow.
But the real fight is joined between the Jewish mother from hell, superbly portrayed by Barbara Young, whose wishful, wrong-headed but well rehearsed knowledge of Jewish family customs and laws, has her turning spitefully on her daughter-in-law Ruth whom she sees as an outsider.
Played by Gwyneth Strong as a convinced and deeply knowledgeable convert to the Jewish faith, Ruths credentials can still come under attack with a well aimed cruel word, gesture or punch line. But the ding-dong between these two women is surely at the very heart of the debate.
I am not sure if the many layers and parts brought together in this play quite work as a cohesive drama, but there is absolutely no doubt that at the Richmond second night the audience was having a ball especially those quick in the uptake when Ms Youngs oldster gets into her destructive stride.
In attractive support, Jessica Dickens makes what I think is her theatre debut as Roths daughter, while Paul Brightwell gives full value with his compromising watch repairer who breaks the news in the opening scene, and then an elegant Ribbentrop at a transforming moment suggesting an altogether more intelligent and enlightened being than this notoriously arrogant but stupid real-life diplomat.
Generously supported by John Lewis and Waitrose, Von Ribbentrops Watch played just a few nights at the Oxford Playhouse and then at the Watford Palace (which is run by the plays director Brigid Larmour), before opening for another week at Richmond.
This short tour finally ends at Salisbury Playhouse from 12 to 16 October and it seems odd that such a lively and accessible comedy has not been taken up by other venues.