Thomas Lascelles (variously spelled both Lascelles and Lassells) (c. 1624 – c. 1658) was an officer in the Commonwealth’s army and a landowner, responsible for Mount Grace Charterhouse, one of the few extant buildings from the period of the English Commonwealth.
Lascelles was born in 1624, the son of William Lascelles and Elizabeth Wadeson. His brother was Francis Lascelles, who was an MP for the constituency of Northallerton and was involved in the trial of Charles the First.
During the Commonwealth period, Thomas was a Captain in the army of Parliament (a Parliamentary note making it clear he had been in service since 1644) and served under Major General Thomas Harrison during the 1650s. He may well be the same man responsible for the capture on 1 April 1650 of Royalist privateer Captain Joseph Constant and his 30-man Dutch crew. After Constant's being sighted off the Yorkshire coast by a local fisherman, Lassells and Robert Colman led an attack party which surprised and captured them.
In 1654 Thomas acquired Mount Grace Charterhouse and transformed part of the western range of the outer court into a house. This remains as a rare example of Commonwealth building in the UK.
Thomas died in or soon after 1658, as emerges from a 1672 inheritance dispute between his widow Ruth and their grandson, also named Thomas Lascelles, who was the heir of Mount Grace.
Another Thomas Lascelles elected Member of the Parliament for Northallerton in the Convention Parliament of 1660, has been misidentified as the same already deceased man. There were several gentlemen of the name in Yorkshire around this time who were probably related. After a gap of nearly thirty years, this Thomas was returned again in 1689 and 1690, and then for the final time in 1695. In addition to his role as MP, he served as 'Housekeeper of the Excise Office' from 1693, with a salary of 200 pounds per annum, and was a captain of militia at the time of his death.
Lascelles died in 1697 and was buried at Northallerton on 4 November 1697; none of his descendants sat in Parliament. He was a sitting MP and left his wife to approach Parliament for help in administering his estates. The House of Lords introduced, "An Act for vesting the Real Estate late of Thomas Lassells Esquire deceased, in Trustees, to be sold, for the Payment of his Debts." The Bill was passed on 25 March 1699, allowing his wife, Rebecca, to dispose of lands and houses in Ealing, Middlesex.