Seymour may have begun his career in the service of Richard Foxe, Bishop of Winchester. By 1526 he had followed his father and siblings into royal service, although he does not seem to have shared the ambitions or abilities of his brothers, Edward and Thomas, and did not progress at court. He served under four Tudor monarchs, although for the most part, he lived in relative obscurity and did not seek honours and preferments. He held a number of offices, including:
He was, presumably, the Henry Semer who was Catherine of Aragon's carver. In 1536 he appears to have replaced Mark Smeaton in the privy chamber and following his sister's marriage, he was appointed to several offices chiefly related to the administration of her estates, some of which he lost at her death. Jane left him "several valuable chains" in her will in 1537. He was carver in the households of Anne of Cleves and Catherine Parr. The queen's jewels were placed in his custody in November 1541 following Catherine Howard's arrest. In 1544 he was made captain of the ship Lyon of Hamburgh under the command of his brother Thomas, Lord High Admiral, but was held to be culpable whe in Novembern it foundered in the Dart estuary during a storm. He was offered no further military or naval command following this incident, and some time in 1545, lost his position in the household of Catherine Parr. He was made a Knight of the Bath in February 1547, soon after his nephew's accession to the throne. In the autumn of 1547, he was elected MP for Hampshire. He is not mentioned in the diaries of Edward VI, although he received a number of royal grants of land during the reign of his nephew. While both his brothers were executed after conspiring against their rivals in their struggles for power, Henry Seymour appears unscathed. In 1549, his brother, Edward, Lord Protector of England, wrote to him and asked him to bring troops to support him. It seems Henry Seymour did not respond, and did well under the administration of his brother's replacement, John Dudley, 1st Duke of Northumberland. He was the sole executor of his mother's Will following her death on 18 October 1550, by which she bequeathed "various legacies of plate, jewels etc. to her relations." In 1551, he was granted the manors of Marvell and Twyford, which had constituted a portion of the estates of the bishopric of Winchester, and the following year, grants for life of the manors of Somerford and Hurn, in the parish of Christchurch, with other lands to the value of £202 6s. 9d. During the reign of Elizabeth I, he was High Sheriff of Hampshire for 1568–69.
Marriage and issue
Henry Seymour married Barbara, the daughter of Morgan Wolfe, and by her had three sons and seven daughters:
