Long before Bernard Delfont or Cameron Mackintosh, London’s greatest – some would say most notorious – impresario was a self-invented society woman who went by the name of Mrs Cornelys. For decades, her riotous gatherings were the talk of the town, but if her rise was meteoric, her fall was positively headlong.

An engraving that appeared in Oxford Magazine: The Remarkable Characters at Mrs Cornelys’ Masquerade

Born Anna Maria Teresa Imer in Venice, her earliest career was as an operatic soprano whose first child, according to rumour, was nearly born on stage in Vienna in 1746. After a period spent touring Europe with Gluck, her third child – by no less a rake than Casanova – was born in 1754. Although she boasted a host of lovers, she also gained a reputation for getting things done and was briefly put in charge of all the theatres in the Austrian Netherlands.

Her first London appearance on tour in Gluck’s La Caduta de’ Giganti had gone down like a lead balloon, but in 1759 she decided to bid Europe farewell and set up home in England claiming to be a widow and using as her surname the...