He was educated in Bury St Edmunds and at Gonville and Caius College, Cambridge, graduating BA in 1751.

In October 1793, he became involved in a dispute with the Parys and Mona Mine companies over the demolition and rebuilding of Amlwch parish church.

The bishop claimed that the mining companies had promised to rebuild the church; they denied this, but eventually agreed to make a financial contribution.

Warren had appointed his own nephew Registrar of the diocese of Bangor, even though the latter was under age.

[3] When the bishop attempted to sack the Deputy Registrar, Samuel Grindley, Grindley refused to leave his office, and a tussle ensued in which the bishop was threatened with a pistol and had to be dragged away by his wife.