Seaburgh held a considerable number of properties in Colchester. In 1380 he obtained rents of £5 a year from the lands of John Christian; he was granted 15 acres in the town in 1384; by 1387 he was holding three plots, upon one of which he had built a house, and in 1398 he purchased a messuage from John Pod, with whom he subsequently occupied premises in All Saints’ parish. In right of his wife he possessed another messuage in New Hythe. He does not appear to have pursued territorial interests outside the town, although in 1407 he became a feoffee of several acres in Salcott, Layer Marney and elsewhere.
Seaburgh was active in the government of Colchester for more than 20 years, beginning in 1384. He was chosen for a jury empannelled in the courts at Westminster in May 1387, in a suit brought by Sir Thomas Swinburne concerning other local men, and he was returned to Parliament in 1397 during his fourth term as bailiff. In January 1398 he represented the town at the Exchequer following royal demands for the full fee farm, and he was again selected to do so in May 1400 when pressure for payment was renewed. In 1405, as bailiff, he received instructions from the archbishop of Canterbury ordering the confiscation of all books written in English, this being part of a move to unearth the heretical writings of the lollards. At the parliamentary elections of 1388 (Sept.) and 1402 he appeared as mainpernor for Simon Fordham and Thomas Godstone, respectively.
On 11 Jan. 1410 Seaburgh and his wife completed enfeoffments of all their lands, tenements and services in Colchester; and he made his will on 1 Feb. following. In this he asked to be buried in the cemetery of St. Nicholas’s church under his family gravestone, and left bequests to the church (including £20 to build a new roof over the chancel), and for works on St. Paul’s cathedral in London. His widow was to have their dwelling in St. Nicholas’s parish and all his other property in Colchester for life provided that she stayed single, with remainder to his sons, John and Robert. The will was proved by Archbishop Arundel at Lambeth on 19 Apr.
