Like his presumed kinsman James Janyn*, John probably came from Ewell in the north of Surrey, where he is known to have held land, and served for a while as constable.
During his long tenure of the post of keeper of the park Janyn became well known in Guildford. He was present at the shire elections held there in 1417, and was admitted to the guild merchant in October the following year. Geoffrey Mudge†, a former MP for Guildford, named him among the feoffees of land elsewhere in Surrey in the 1420s.
During the 1420s Janyn was occasionally a defendant in suits for debt filed in the court of common pleas. As ‘of Ewell’ he was subject to a plea brought by the executrix of John Halle senior of Sussex for a debt of £20, and the influential Sussex landowner Sir Roger Fiennes* alleged that he owed him 20 marks. In 1425 Thomas Carew sued him for a breach of the Statute of Labourers for abducting a servant from his employment, although Janyn denied the charge.
Of Janyn’s landed possessions there is scant record, although in 1435, together with Hugh Ashbury* (a fellow Member of both his Parliaments) he acquired an interest in a messuage, ten acres of land and an acre of meadow in Guildford and nearby Stoke, and according to the tax assessments made shortly afterwards his annual income from land in Surrey amounted to £10.
