John Carter Allen himself had been baptised at St Dunstan in the West in 1724/5, the son of Carter Allen (1700-1734), an attorney in the parish of St Clement Eastcheap in the City of London, who had married Emma Hay or Hays at St Giles, Camberwell, in 1724. These details also were not known until 2014. Contemporaries of John Carter Allen had said at his death in 1800 that the late Lord Hillsborough (who died in 1793 and for whom John Carter Allen’s younger brother William Allen (1729-1811) had worked as an office clerk) had said that ‘he had a claim to the title of Erroll ... as being descended from the old Earl Hay in the male line’, a worthless statement as the peerage had become extinct in the male line in 1717, but believed by Thomas who added Hay to his name.