[1] He was born at Kirkby Stephen in Westmoreland in 1544 and was educated at Sedbergh School, Thereafter, he entered St. John's College, Cambridge, where he graduated B.A.
On 13 August 1579, he was presented by Sir William Spring to the rectory of Cockfield, Suffolk, in succession to Richard Longworth, and continued to hold the living for the rest of his life.
In May 1582, an assembly of about 60 clergymen from Norfolk, Suffolk, and Cambridgeshire met in Cockfield Church to confer about the Prayer Book, clerical dress, and customs.
[4] Knewstub was a strong candidate in 1595 to succeed William Whitaker as Master of St John's, though Richard Clayton was elected.
The work was dedicated to Ambrose Dudley, 3rd Earl of Warwick, and the contents of the volume show that Knewstub was, by this time, well known at court.