John James (Johann Jacob) Heidegger (1666 - 1749) was a leading impresario of masquerades in the early 18th century. He came to England in 1708, leaving Switzerland 'in consequence of an intrigue.' After trying his hand at various occupations, he became influential in opera, writing and directing. From 1710 he promoted masquerade balls at the Haymarket Theatre. London’s fashionable set loved this new form of entertainment, and lauded the ‘Swiss Count,’ despite the protestations of clergymen and moralists, who worried about immoral influences. Much of the pleasure and excitement associated with the balls resulted from the aura of sexual danger and mystery, and women of pleasure were always present.
Heidegger and Handel enjoyed a long collaboration, producing operas at the King's Theatre to great acclaim.
Heidegger is alleged to have boasted: "I was born a Swiss, and came to England without a farthing, where I have found means to gain 5000 a year, — and to spend it. Now I defy the ablest Englishman to go to Switzerland and either gain that income or spend it there.”