After Frederick's death, Nattrass soon became Mary Ann's lodger. She gained employment as nurse to an excise officer recovering from smallpox, John Quick-Manning. Soon she became pregnant by him with her thirteenth child. It may well be that the name of the excise man was in fact Richard Quick Mann as there appears to be no trace of a John Quick-Manning in the records of the West Auckland Brewery or the National Archives. The census records, birth, death and marriage records also show no trace of him. Richard Quick Mann was a custom and excise man specialising in breweries and has been found in the records and this may be the real name of Mary Ann Cotton's alleged lover.
Frederick Jr. died in March 1872 and the infant Robert soon after. Then Nattrass became ill with gastric fever and died just after revising his will in Mary Ann's favour.
The insurance policy Mary Ann had taken out on (the still living) Charles' life still awaited collection.