Carr was returned once for Newcastle, to the same Parliament as his brother-in-law William Jenison I. Another brother-in-law, Bertram Anderson, had been returned in 1563. Carr had extensive lands in Newcastle, elsewhere in Northumberland and in Yorkshire. His main estate at Houghton may have been part of his marriage settlement. He left a rent of 40s. for the free school and the poor of the parish.
Carr’s wife’s nephew, John Trollop, fled after being implicated in the Northern rebellion, and Carr evidently appealed on his behalf to the 4th Earl of Morton, who on 16 June 1570 wrote to Sir William Cecil asking him to be lenient to Trollop ‘for the sake of one William Carr of Newcastle, my ... friend, whom I know to be honest’. Carr’s connexion with Morton may have been through the Bowes family, who must have known the Earl well. Carr made his will 10 June 1572, ‘touched in my body by the hands of God with infirmities and sore diseases’. He wished to be buried in the church of St. Nicholas, Newcastle, ‘as near to my great-grandfather George Carr as can be’. The Carrs continued to be well-known Newcastle merchants for over a century.