A mirror from Lady Coventry’s boudoir will go on sale this week.

The George II giltwood overmantel mirror sat in Lady Coventry’s dressing rooms at Croome Court, the Worcestershire seat of the Earl of Coventry, near Upton-upon-Severn.

It was bought for the 6th Earl of Coventry’s first wife, Maria Gunning, and has an estimate of £200,000 to £300,000.

The mirror has a tragic story behind it as Maria, a famed beauty, died a year after it was ordered, with her skin ravaged from the lead-based white powder popular at the time.

Jill Tovey, Croome archivist, said: “The 28-year-old Earl of Coventry, who had just inherited Croome, was in need of a wife and who better then the lovely Maria – so lovely, we hear, that crowds stood in Hyde Park to see her pass by and people fainted in the crush.

“The story goes, that a shoemaker in Worcester made quite a lot of money by charging people sixpence, just to see her shoes.

“But, the story ends sadly – she contracted consumption and, probably made worse by the white lead make-up she’d used, she died at Croome in 1760, aged only 29 – reputedly hidden away with only the light of a tea-kettle, so upset was she about her ruined beauty.”

The mirror is Lot 100 of an auction of furniture, paintings, porcelain, and works of art and silver from Mount Congreve, Ireland.

The auction takes place at London auction house Christie’s tomorrow.

The mid-18th century mirror is described as being seven-foot tall and surmounted by an elaborately pierced and carved basket of flowers above acanthus scrolls and mirrored borders.

It was designed by the cabinet-making father and son firm of William and John Linnell in 1759.

An invoice dated 18 August 1759 describes a similar overmantel intended for the dressing room of Lady Coventry.

It is believed the mirror, one of the highlights of the sale, was previously sold in a famous 1948 auction of Croome Court furniture.