Clavell, John (1601–43), adventurer, was born on 11 May 1601, sixth child and second son of John Clavell and his wife Frances Willoughby of Wootton Glanville in Dorset, England. He was admitted to Brasenose College, Oxford, in 1619, pardoned for decamping with the college plate in April 1621, sentenced to death for a series of highway robberies in January 1626, reprieved on foot of a general amnesty when Charles I was crowned in the following month, and received his second royal pardon in November 1627. A verse Recantation of an ill led life (1628) attracted favourable attention, and he had a five-act play performed by the King's Company before leaving for Ireland in August 1631.
His purpose was to litigate for lands in Carrigcrohane, Co. Cork, on behalf of his uncle, Sir William Clavell, who had been in the service of the lord president of Munster and been knighted by Essex (qv) in 1599. In addition to whatever connections Sir William may have had, Clavell's friendship with Thomas Naylor, a Kentish student at Grey's Inn who was related to the earl of Cork (qv), may have provided him with an entrée to Munster society. The suit seems to have been unsuccessful but Clavell made a large impression. Lord Barrymore (qv) testified, in a letter to Sir William, to the widespread regard in which he was held, by the earls of Cork and Ormond (qv) and by the lord chancellor, Viscount Loftus (qv), among others. He appears to have owed his introduction to Loftus to George Kirke, a groom of the bedchamber.
Clavell went to England to report to his uncle in September 1633 and returned to Dublin in December 1634, where he enjoyed the patronage of Loftus, who allowed him to practise at the bar and through whose influence he was admitted to the King's Inns in November 1635. On 14 April 1635 Clavell married Isabel Markham, the nine-year-old heiress of a Dublin vintner who was a member of the lord chancellor's circle. During this second visit, he set up in practice as a physician, at first in Co. Cork in 1636, where his patients included Sir Randall Clayton; later, in Dublin, where he treated Loftus and members of episcopal, noble, judicial, and aldermanic families with, by his own account, unvarying success. Sufficient of his prescriptions survive to indicate that he was a serious practitioner who studied both folk remedies and physic and eschewed the prevailing astrological fashion.
Clavell left Ireland in June 1637, entrusted by the earl of Cork, who described him succinctly as ‘the physicall lawyer’, with a commission in connection with his manor of Stalbridge in Dorset (A. B. Grosart (ed.), Lismore papers (1st ser., 1886–8), v, 12). Clavell subsequently became involved in protracted litigation in London about a disputed bond and died on 17 February 1643. He was not, as has been assumed, without issue: Isabel ‘and her fatherless child whome these unfortunate tymes have also quite stript of all their fortunes and means’ were living with her widowed mother in Dublin in May 1646 (TCD MS 810, f. 337).