The Mansell family traced their ancestry back to a follower of William the Conqueror. During the fourteenth century they settled in the Gower peninsula, in South Wales, and after some advantageous marriages they established residences at Oxwich and Penrice.
Although he seems not to have attended university, Mansell travelled on the continent during his early twenties and was praised in bardic eulogies as a scholar and ‘mirror of gentility’.
Having been returned for Glamorgan in 1597, Mansell was evidently willing to allow secretary of state Sir John Herbert* to take the seat in 1601. As sheriff in 1604, he was prevented from standing at that year’s general election, when the county seat went to Sir Philip Herbert*, a favourite of the new king, and brother of the most powerful landed interest in Glamorgan, William Herbert, 3rd earl of Pembroke. However, in 1605, Sir Philip’s elevation to the peerage as earl of Montgomery allowed Mansell to be returned at a by-election, and in 1614 he took the seat again.
Although not a vocal Member, Sir Thomas was nominated to committees and conferences on a wide range of topics. His committee appointments suggest an interest in religion: he was named to the committee for the Sabbath bill and later appointed to attend a conference with the Lords on this subject (29 Jan. 1606 and 1 June 1614). He was also nominated to bill committees regarding recusants and non-resident clergy as well as a conference on ecclesiastical grievances (3 Feb. and 10 Apr. 1606; 12 May 1614).
Some of Mansell’s nominations related to Welsh issues, or touched upon his interests as a magistrate, in which office he proved assiduous.
Mansell’s parliamentary interests were not restricted to Wales and the Marches, for since James’s accession he had spent considerable time at Court, thereby troubling bards such as Dafydd Benwyn, who voiced concern at Mansell’s increasing periods of absence.
Mansell obtained one of the first baronetcies in 1611, being third in precedence, and served as a canopy-bearer in 1612 at the funeral of Prince Henry.
During the 1620s Mansell continued to play a prominent role in local politics and administration, especially as a deputy lieutenant during the wars with Spain and France.
Mansell’s standing at Court and within Glamorgan allowed him to marry off his son and heir, Sir Lewis, to a daughter of Viscount L’Isle (Robert Sidney†) and then to a daughter of the 1st earl of Manchester (Sir Henry Montagu*).
Mansell was regarded as a shrewd manager of his estate, and he was also a major moneylender, having over £4,000 loaned out upon mortgages at his death.
