"My dearest Diana, you must be the vainest woman in the world." So says one of the men who dotes on Diana Lenton, the heroine of this debut historical romance. The ranks of her admirers could populate a small village; her sins--among which vanity is the least heinous--deserve a salute from Beelzebub. But, as the author labors to make clear, Diana has reason for being such a wicked--if classy--bit of baggage: In the year she's slated to come out (1927), it's revealed that her Papa was involved in a seedy bit of business that upset the Labour Party back in 1924, but failed to win him and his Russian mistress the big bucks he'd hoped for. Meanwhile, Diana's insanely jealous mother takes out her hostility on her daughter, thus heaving Di into the arms (and bed) of the young American millionaire Ben Lassiter. Alas, she and Ben quarrel (over her daddy's reputation), causing her to marry old standby Roland Lenton and flee to Malaya--where she bears Ben's son (Cosmo), has a fling with a Danish mariner, learns of Roland's homosexuality, has another son, and narrowly avoids the Japanese occupation. Back in England, it's Di first, as usual, as the war winds down and she works to return Roland's Devonshire estate to its former grandeur. Meanwhile, she learns interesting tidbits about her father and late husband Roland, and finishes just as Waspishly as she began--by blackmailing her son with secret information about his own incestuous marriage. This has some inventive strokes and exotic backdrops; but the plot's an unruly mishmash, and the heroine, an ill-conceived witch.