A leading European castrato in the second half of the eighteenth century, Manzuoli sang to great acclaim in Madrid, Lisbon, Vienna and Bologna before heading to London`s King`s Theatre for the 1764-1765 season. Leopold Mozart`s letter from London to his friend Lorenz Hagenauer (8 February 1765) gives a good indication of Manzuoli`s esteemed reputation at this time (and the rich rewards he received): `This winter, nobody is making much money except Manzuoli and a few others in the opera. Manzuoli is getting 1500 pounds sterling for this season and the money has had to be guaranteed in Italy … otherwise Manzuoli would not have come to London. In addition he is giving a benefit, that is, an evening recital for himself, so that this winter he will be drawing more than 20,000 German gulden. He is the only person whom they have had to pay decently in order to set the opera on its feet again`. Manzuoli elicited lavish praise from Charles Burney: `Manzuoli`s voice was the most powerful and voluminous soprano that had been heard on our stage since the time of Farinelli; and his manner of singing was grand and full of taste and dignity`. Baron Friedrich Melchior Grimm also remarked in the Correspondance littéraire of 15 July 1766 that he `sings with as much taste as soul`.
Manzuoli befriended the Mozart family in London in 1764-1765, and probably gave Mozart singing lessons. He also performed a private concert with the Mozarts at the home of Lord and Lady (Robert and Margaret) Clive in Berkeley Square. They met in Florence in 1770, first by chance on 2 April, and again in Milan in late 1771, when Manzuoli sang Ascanio in the first production of Mozart`s Ascanio in Alba (17 October 1771), written for the wedding of Archduke Ferdinand of Austria and Maria Beatrice Ricciarda of Modena. But a disagreement over Manzuoli`s fee ensued, as reported by an irritated Mozart to his sister on 24 November 1771: `Manzuoli, who up to the present has been generally looked upon as the most sensible of the castrati, has in his old age given the world a sample of his stupidity and conceit. He was engaged for the opera at a salary of five hundred cigliati, but, as the contract did not mention the serenata, he demanded another five hundred for that, that is one thousand cigliati in all. The court only gave him seven hundred and a fine gold snuff-box (quite enough, I think). But he like a true castrato returned both the seven hundred cigliati and the snuff-box and went off without anything. I do not know how it will all end—badly, I expect`.
I. Woodfield, `New Light on the Mozarts` London Visit: A Private Concert with Manzuoli`, Music & Letters 76 (1995), 187-207