From the "Calendar of Entries in the Papal Registers Relating to Great Britain and Ireland" Published 1893. Printed for H.M. Stationery Office, by Eyre and Spottiswoode
Dated Kalends of May 1440
"To William Barnet, rector of Sutton in the county of Surrey, in the diocese of Winchester, B.C.L. Dispensation to hold for life with the said church, value not exceeding 25 marks sterling, one other benefice with cure etc, as above f. 189d. Litterarum etc (An. and Cyprianus. | An. L. de Adria.)"
William Barnet seems to have died in 1451. His will is below:
"1451 P.C.C. 16 ROUS (Latin Will) Wiliam Barnet, clerke, SUTTON, Surrey.
Rector of parish church of Sutton. Dated 17th March, 1450-1 29th Henry VI. To be buried at discretion of Executor in church of the parish where God ordains that I die. Residue of goods etc. after payment of debts and funeral to my Executors John Hincheman and Matilda his wife, my kinswoman.
Probate 20th April 1451 by aforesaid Executors"
Source: Hooper, H. J. 'Some Surrey wills in the prerogative court of Canterbury, 1'. Surrey Archaeological Collections, 51
There is nothing to indicate from what cause William Barnet died but 'Parts of England experienced plague epidemics in 11 out of the 18 years between 1442 and 1459'.
Source: GOTTFRIED, Robert S (1983), The Black Death: Natural and Human Disaster in Medieval Europe, London: Robert Hale.