He accompanied Henry VI to France in 1430, was summoned to Parliament from 25 February 1432 to 30 July 1460 by writs directed to Leoni de Welles, and was a privy councillor before 12 November 1434.

From 12 February 1438 he resided in Ireland as Lord Lieutenant; according to Hicks, he 'failed to control the contending factions and resigned prematurely in 1442'.

In 1441 he was particularly embarrassed at his inability to prosecute Thomas FitzGerald, the Prior of the Knights Hospitallers at Kilmainham, whom he accused of being party to the kidnapping of Lionel's brother William.

Despite these appointments, according to Hicks, Welles was 'essentially a Lincolnshire landowner'; he was a Justice of the Peace and served on other commissions in that county.

[5][2] He was installed, together with John Talbot, 2nd Earl of Shrewsbury, as a Knight of the Garter on 14 May 1457, and in October of that year was sent with English reinforcements to Calais.

and Methley, Yorkshire,[2] and his wife, Cecily Fleming, daughter of Sir Robert Fleming of Woodhall (brother of Richard Fleming, Bishop of Lincoln), by whom he had one son and four daughters:[10] Secondly, by licence dated 14 April 1447, he married Margaret Beauchamp, widow successively of Sir Oliver St John (d.1437) and John Beaufort, 1st Duke of Somerset (d. 27 May 1444), and daughter of Sir John Beauchamp of Bletsoe, Bedfordshire, by his second wife, Edith Stourton, daughter of Sir John Stourton, by whom he had one son:[10] By his second marriage Welles became the stepfather of Margaret Beaufort, mother of Henry VII.