Thomas Harris heard Incledon at Bath, and engaged him, at first for three years, for
Covent Garden. In accepting this offer the tenor narrowly missed a better one – for higher fees and a longer term – made soon afterwards by
Thomas Linley. Incledon kept his agreement however, although his experiences with Covent Garden were not always of the happiest. He made a successful debut there in 1790 as Dermont in
The Poor Soldier by
William Shield, who became a lifelong friend and associate. In February 1791 he appeared in Shield's opera
The Woodman, being universally encored in his ballad 'The streamlet', and with
Charles Bannister in the same cast singing 'Much more a helpless woman'. In 1793 he made a short Easter tour with Bowden, Mrs Martyr and the oboeist William Parke, to Portsmouth, where they were very well received. February 1794 introduced him in Shield's
The travellers in Switzerland in a cast with Miss Poole, Mrs Martyr and Mr Fawcet; and in April in a new work,
Netly Abbey (a compilation from various composers) Incledon sang Shield's old song 'The Arethusa', which he had already made his own. Incledon's performances, and Shield's new operas, 'made him so popular that for several years he travelled in the summer, and at every considerable town in England gave an entertainment consisting of recitation and songs (on Dibdin's plan), with great applause and profit.' At Covent Garden a notable production was the revival of ''
The Beggar's Opera in October 1797, with Madame Mara (engaged for twelve nights at huge cost) as Polly and Mrs Martyr as Lucy. Incledon was thought unrivalled as MacHeath. In 1800 the two-act Paul and Virginia'' (music by Mazzinghi and Reeve) gave Incledon two pieces, one a spirited air with oboe obbligato, and the other, 'Our Country is our Ship' by Townshend won him a general encore. In 1800 also he earned the distinction of singing in the London premiere of Haydn's
The Creation on 28 March in the composer's presence. In February the following year,
Thomas Arne's opera
Love in a Village was revived for
Mrs. Billington, into which she introduced
William Boyce's duet 'Together let us range the fields' for herself and Incledon, which was loudly encored. In the same month was presented a new comic opera written by Dibdin,
The Cabinet (the music by various composers), in which Incledon appeared together with
John Braham and
Nancy Storace, and in delivering the hunting song 'his fine volume of voice filled the whole theatre'. Incledon's MacHeath was reprised at
Margate in August 1803. Another new Dibdin opera,
The British Fleet in 1342 (music entirely by Braham) appeared in December, and on that evening the highlight was a duet by Braham and Incledon, 'All's Well', which was encored. At Covent Garden, Incledon successfully took on as a tenor several important roles created by his friend the celebrated bass
Charles Bannister, about a generation after the original productions. Thus he appeared as Tom Tug in Dibdin's
The Waterman (first presented at the Haymarket in 1774) and in 1809 took the role of Mr. Steady in Dibdin's
The Quaker (first presented at Drury Lane in 1777). In 1810, similarly, he appeared as the Serjeant in
Isaac Bickerstaffe's musical entertainment of
The Recruiting Serjeant (formerly produced at the
Royalty Theatre in 1789, first 1770), and in 1814 as Mr. Belville (another Bannister role) in Mrs Brook's opera
Rosina (presented first at Covent Garden in 1783). Since the airs or ballads in these musical dramas stood alone with spoken dialogue, the transposition from bass to tenor did not create excessive difficulty. After singing in that theatre for many years, and after several disagreements with Harris, he finally withdrew, and 'soon after took a parting benefit at the Italian Opera House, at play-house prices, assisted by many of his brethren of both theatres, to a house filled to an excess that proved how highly his talents were appreciated.' ==The singer among his contemporaries==