In 1822 he married Elizabeth Sarah Rahn, whose family had arrived in England from France following the revocation of the Edict of Nantes.
[1] They had three sons (Edward Hadham, John and Conrad Rahn) and two daughters (Elizabeth and Mary Augusta).
[2] He died at his home in Islington and was buried at Theydon Garnon, Essex.
[1] Nicholl extended an interest in his own family's genealogy to that of the wider Essex gentry and worked on the archives of the Ironmongers Company (of which he was a member).
In 1842 and 1843 he traveled in Europe, compiling architectural and landscape sketches and collecting further genealogical material.