During Henry V's reign he became Archdeacon of Salisbury, but by early 1421 had been appointed King's Secretary, and is recorded as attending Privy Council meetings.
[8] While at Lincoln Alnwick attempted a resolution of a dispute within the cathedral, producing an elaborate arbitration.
He then reviewed the whole body of statutes of the diocese, then largely unaltered since the Norman Conquest, creating an improved one.
Alnwick was an assiduous heresy-hunter, and persecutor of the Lollards, punishing them with imprisonment, forced entry into monasteries and, in at least one case, execution.
In his will he left money to St Michael's Church, Alnwick, as well as vestments, a missal, an antiphoner, and a chalice.