His practice justified his being regarded as a candidate for the office of solicitor-general, but he was passed by, possibly because, as the satirists alleged, his manners were stiff and pretentious.
On the death of Sir Thomas Abney in 1750 Gundry was appointed a judge of the common pleas.
After he had been on the bench four years he, like Abney, was carried off by gaol fever, while on circuit at Launceston, Cornwall, on 23 March 1754, aged 53.
He was buried at Musbury, near Axminster, and a tablet to his memory was placed against the western side of the south aisle of the parish church.
A leasehold interest in the farm of Uddens in Chalbury, Dorsetshire, was acquired by him, and he built on the property a mansion which passed to his son Nathaniel, but he resided at Maidenhayne in Musbury, which he held on lease from Lady Drake.