Whilst the Mills stand in the Parish of Clayton, there may be an overlap of interest with Keymer Parish which extended Northwards embracing what is now the considerable town of Burgess Hill. Hence the complexity.
The Census of Sunday 6th June 1841 has this preamble: "Each person who abode therein the preceding night".
The Enumerator compiling this return wrote an 'unfamiliar' hand so that copies available are difficult to decipher.
Additionally, as many of the population were illiterate,
there could be no certainty of correct spelling of surnames dictated in a variety of dialects.