A deliverer was an official charged with delivering or witnessing royal writs or grants. The phrase 'neither writ nor deliverer' implied that an estate was held without royal authority. It has been suggested that such officials may have held sergeantry tenures which go back to the Conquest, or even earlier, though the word itself is first recorded in Domesday Book.
For more detail, see R.R. Darlington, 'Introduction to the Wiltshire Domesday', Victoria History of the county of Wiltshire, vol. 2, edited by R.B. Pugh and E. Crittall (1955), pages 42-177; James Campbell, 'Some agents and agencies of the late Anglo-Saxon state', in Domesday studies, edited by J.C. Holt (Woodbridge, 1987), pages 201-18.