Mason should not be confused with two namesakes, Robert Mason I* and Robert Mason†, who as father and son represented Winchester in the early Stuart period and at the Restoration respectively.
At the 1626 general election Buckingham nominated Mason for the second seat at Ludgershall, but a close contest between him and Sir Thomas Jay* ensued, resulting in a double return. The Commons resolved the dispute by ordering a fresh election for that seat, whereupon Mason withdrew his candidacy.
Despite his patron’s untimely death, Mason was appointed chancellor of Winchester diocese in 1628, and in the following year he became commissary to the archdeacon of Surrey. His work in these offices was interrupted by occasional travels abroad. While touring Italy in 1631 he was delayed at Padua after the town was quarantined because of the plague. He enrolled at the university there in April, presumably to avoid the censure of the local Catholic authorities. In 1636 he was at The Hague, from where he informed Edward Nicholas* of the movements of French and Dutch troops and of the proposed treaties between those nations and Spain.
Mason was possibly attached to the Court at Oxford in May 1643, since his signature appears in papers drafted on behalf of the king concerning a petition for the keepership of the royal mews at Greenwich, in which he may have had an interest.
