He collected aid in Northamptonshire between 1235 and 1236, and in 1240 was appointed as a royal justice, acting almost continuously until 1254 as a puisne justice on the Eyre circuits of William de York, Roger of Thirkleby and Henry of Bath, and in the common bench at Westminster.
He also received many miscellaneous judicial and administrative commissions, and was given a regular salary of £40 in 1253, after 13 years of judgment.
[1] In 1254 Gilbert served as senior justice on an Eyre circuit for the first time.
In 1239 Gilbert married Alice, daughter of Henry of Braybrooke, with whom he had no children.
As a result he left his possessions to his nephew Laurence of Preston, son of his younger brother William who had predeceased him.