Lowther’s father, William, was the youngest of the seven uncles of John Lowther I*, and thus represented the most junior line of this Westmorland gentry family. William owed his Ingleton estate to his brother, Sir Gerard Lowther†, an Irish judge, who first allowed him to settle there, then in 1620 conveyed the property to him, along with the advowson and rectory of the local parish.
In January 1626 the electors of Berwick-upon-Tweed failed to agree on how to dispose of the borough’s second parliamentary seat. In the ensuing confusion Lowther was successfully nominated for the vacancy, conceivably by his kinsman Henry Clifford, Lord Clifford*, the joint lord lieutenant of Northumberland. Elected no later than 6 Feb., Lowther initially wrote from Lowther Hall to thank the borough, but then presented himself two days later at Berwick, where he was sworn as a freeman, and entrusted with delivering his own election indenture to Westminster.
In 1630 Lowther and his father sold the St. Bees estate to Sir John Lowther for £2,450. The Ingleton lands generated an income of only around £140 p.a., but this was sufficient to secure Lowther’s appointment as a Yorkshire magistrate in 1634. However, he was removed two years later, apparently because his father was being restored to the bench.
