Inheritor of a ducal fortune who owned estates in Caithness; Born September 16, 1916; Died December 21, 2008.

Lady Anne Cavendish-Bentinck, who has died aged 92, made front-page news in 1937 when she was told to accept the hand in marriage of Prince Charles, the nobleman destined to be prince regent of Belgium. The resultant story described the wilful Lady Anne as declining to get out of bed when the luckless suitor arrived at her home - though the tale was adorned and enhanced when a rumour emerged that she was tipped to marry the widowed King Leopold III rather than his brother, Charles.

She later set her sights on the handsome Duke of Leeds, but her family refused her permission to wed and defiantly she vowed never to marry anyone else. She kept her extraordinary promise for the rest of her life.

Lady Anne, reputedly one of the wealthiest women in the UK with a personal fortune estimated at £158m, was a cousin of the Queen Mother and owned some 62,000 acres in Scotland, including lairdship of the estates of Braemore and Langwell in Caithness. She also possessed a fabulous trove of art treasures, including works by Stubbs and Van Dyke, plus a huge silver collection held in a strongroom said to be as large as a small house. But her largest single asset was almost certainly 30 near-priceless acres around Harley Street, London.

Alexandra Margaret Anne Cavendish-Bentinck was born the elder daughter of William Cavendish-Bentinck, seventh duke and eighth Earl of Portland; through her mother, the Hon Ivy Gordon-Lennox, she was a direct descendant of Charles II. Had she been male, she would have succeeded her father as eighth duke, but he had no male heirs, resulting in the dukedom passing to a distant relative and dying out in 1980. Through an arrangement of her grandfather, the sixth duke, Lady Anne inherited the family fortune.

Lady Anne cut a formidable figure. In Caithness, in the summer of 2000, Lady Anne drove from Braemore to Barrogill for tea with the Queen Mother, after which her centenarian neighbour was heard to remark: "I've known her since she was a little girl - she was gruff then and she's gruff now."

The earldom of Portland continues, the present earl being actor Tim Bentinck, more familiar to Radio 4 listeners as David Archer. Heir to Lady Anne's fortune is her nephew William Parente, son of Lady Peggy, Anne's sister. GORDON CASELY