What a week it was for . . . the Ewings

Hell hath no fury like a Scottish matriarch upstaged by a younger woman. This was the week when Scotland`s leading political family - the Ewings of Moray - split over adultery and political ambition.

"SNP Sex scandal!" screamed the Glasgow tabloids on Tuesday. Was this sensational revelations of nationalists "caught with their troosers doon"? No. The story was so old that most people had forgotten about it. All, that is, except one - 65-year-old Winifred Ewing of Goodwill, Elgin.

Last weekend the Scottish National Party MEP for the Highlands and Islands used an official campaign meeting for next month's Perth and Kinross by-election to breathe new life into an internal party scandal. It started in the mid-Seventies when Roseanna Cunningham, a rising star in the SNP, was a researcher at party headquarters in Edinburgh. There, she met Donald Bain, a party consultant, who was married to Margaret, the blonde, chain-smoking SNP MP for Moray. But the marriage was shaky and the couple separated. Before the two divorced and Margaret married Winnie's son Fergus, Miss Cunningham began an affair with Mr Bain. The relationship infuriated Winnie.

At the SNP candidates' meeting on Sunday, Miss Cunningham was asked whether she had any "skeletons in the closet" that the localselection committee should know about. She mentioned her relationship with Mr Bain but said that it was ancient history. Winnie exploded with rage. She brought the meeting to a halt, accusing Miss Cunningham of breaking up her daughter- in-law's first marriage.

Astonished and upset, Miss Cunningham repeated that the affair had started after the couple had separated. She left the grilling tearful but determined to pursue her claim to a seat held by the late Sir Nicholas Fairbairn.

By Monday night, however, it was clear that she would have to stand aside. Persistent press inquiries about her past were embarrassing party leaders. At one minute past midnight on Tuesday, she issued a statement saying that she had decided to withdraw, "with great regret". Margaret Ewing offered her sympathy, dismissing her mother-in-law's decision to drag up the past as "foolish and prurient".

The row has thrust the Ewings back into the centre of Scottish political life, a position they occupied throughout the SNP's glory years in the Seventies. The family is Scotland's only political dynasty. Like their American soap-opera namesakes, theirs is a matriarchal line whose success is founded on oil - not the dirty brown gushers of Dallas, Texas, but the black political gold of the North Sea.

During the Seventies, Winnie, elected to Westminster in 1967, and Margaret, who followed her seven years later, helped to lead the SNP's successful "It's Scotland's Oil" campaign. The pair's populist campaigning style won the SNP support and soon, like an oil slick, the influence of clan Ewing began to spread. Winnie became the self-styled Madame Ecosse in Brussels and Margaret took over as the SNP's Westminster leader. Fergus became the nationalists' business affairs spokesman and Winnie's husband, Stewart, later began working as her Highlands and Islands agent. Their daughter, Annabel, recently opened the nationalists' Brussels office.

One Cunningham loyalist says: "Winnie eats, drinks and breathes Scotland. She believes in all the Madame Ecosse stuff. She has made herself an institution - the grande dame of the SNP. She can't stand it when other women appear to be taking on her mantle. Roseanna is 42 and a rising star. Winnie could not resist the temptation to slap her down."

Others point to political divisions. Winnie Ewing is on the right of the party, Miss Cunningham on the far left. All agree that Mrs Ewing bears grudges like no other mother-in-law. One party observer says: "Winnie is a tough old bird. If she takes against someone, that's it. She acted like a mother to Margaret when her marriage broke down and she detested Roseanna because she saw her actions as a threat to her treasured family brood. There's nothing more to this than a mother-in-law's good old-fashioned anger."