Origins of opera
"Dafne" by Jacopo Peri was the earliest composition considered opera, as understood today, although with only five instrumental parts it was much more like a chamber opera than either the preceding intermedi or the operas of Claudio Monteverdi a few years later. It was written around 1597, largely under the inspiration of an elite circle of literate Florentine humanists who gathered as the "Camerata". Significantly, "Dafne" was an attempt to revive the classical Greek drama, part of the wider revival of antiquity characteristic of the Renaissance. The members of the Camerata considered that the "chorus" parts of Greek dramas were originally sung, and possibly even the entire text of all roles; opera was thus conceived as a way of "restoring" this situation. The libretto was by Ottavio Rinuccini, who had written some of the 1587 Medici intermedi, in which Peri had also been involved; Rinuccini appears to have recycled some of the material, at least from the scene illustrated at right. Most of the music for "Dafne" is lost (the libretto was printed and survives), but one of Peri's many later operas, "Euridice", dating from 1600, is the first opera score to have survived to the present day.
Thomas Clayton (composer)
In association with Nicola Haym and Charles Dieupart, Clayton entered upon a series of opera performances at Drury Lane Theatre — the first venture of the kind in the annals of the English stage. 
The first season began on Tuesday, 16 Jan. 1705, with "Arsinoe, Queen of Cyprus", the work which Clayton had vamped up from his Italian gleanings. 
It was announced as 'a new opera, after the Italian manner, all sung,' with recitatives instead of spoken dialogue. 
It seems to have attained some success, though a contemporary writer (supposed to be Galliard) says 'there is nothing in it but a few sketches of antiquated Italian airs, so mangled and sophisticated, that instead of Arsinoe, it ought to be called the Hospital of the old Decrepid Italian Operas,' and Burney was inclined to acquit Clayton of plagiarism in its composition, for 'nothing so mean in melody and incorrect in counterpoint was likely to have been produced by any of the reigning composers of that time.' 
It was sung by Richard Leveridge, Hughes, Ramondon, Good, Mrs. Lindsay, Mrs. Cross, and Mrs. Tofts, the last of whom made in it her first appearance on the stage. 
On 6 February 1705, it was played at St. James's Palace before Queen Anne, at the celebration of her birthday ; according to Genest it was performed fifteen, or according to Burney twenty-four times in 1705, and thirteen times in 1706. The opera has been described as the first English opera in the Italian style.