Corbet, the uncle of Sir John Corbet*, was engaged in quasi-official diplomatic missions to France for most of the 1590s.
The 1st earl of Salisbury (as Cecil now was) doubtless recommended Corbet to the electors of Portsmouth in place of Sir Oliver St. John*, appointed to Irish office. He was returned on 27 Jan. 1607, presumably in his absence, since three days earlier he was suffering from an ague, which he feared would turn to consumption without a change of air.
Corbet’s health broke down during the summer, and on 1 Sept. 1610 he was at Sprowston convalescing from attacks of the stone and the ague; he does not appear in the sparse records of the Parliament’s fifth session.
