It appears that John & Grace lived in the Gears(see map below), which is a small collection of cottages north-west of the town of Goldsithney in Cornwall. Grace died at the age of 47 in 1830 and was buried next to the Perranuthnoe church. A note on her burial details states that she was from the Gears. Her sister in law Hannah James died in 1876 and was also noted as being from the Gears. It seems from this then that the families of John & Grace Sampson and his sister Hannah & Thomas James were based in the Gears. More recent research has indicated that the Sampson family owned plots of land along Gears Lane on the southern side of the Lane near the entrance to the Gears circled in red  below.
To date  the death of John Sampson has remained a mystery as no death record has been found. The last child of John & Grace (Elizabeth) was born in March of 1826 and as John is not mentioned in the 1841 English Census it is assumed he died somewhere in the period of 1826 to the date of the census in 1841.