Corbett joined the navy as an ordinary seaman in 1704, serving under Sir George Byng, whose secretary and trusted assistant he became. In 1712, when he was at Utrecht, where he vainly endeavoured to obtain the post of secretary to Lord Strafford, he wrote to Byng:
I think I may say for myself, I know no intrigue in business but honesty, nor any party, but gratitude to my patrons, and to those who support me in the world. If, to acknowledge the eternal ties I have to you, if to mention your name with the honour I owe you, be to be a Whig, I shall so far glory in the name. Nor would you, I am sure, think the worse of me, if I bore the same respect for any benefactors on the Tory side which I should most certainly, had I the same obligations to them [as] I have to you.
Appointed a clerk in the Admiralty in 1715, when Byng was re-appointed to the board of the Admiralty, he was promoted chief clerk ‘over the heads of all the rest of the staff’
We go on very lovingly and comfortably with our monocular secretary; when one comes to be better acquainted with him, he is not so bad as he looks. It is true he has but one eye, but then he takes the more exact aim at the matters in question with the remaining one, as it is constant economy of nature in all her duplicate dispositions, that one becomes stronger and does double duty when the other is off from guard.
Bedford Corresp. i. 37.
In the end he became so infirm that John Clevland was appointed joint secretary to help him to carry on the business.
