The online index to the 1871 Ontario Census at http://220.127.116.11/census/index.html
lists your John Clouston born: Scotland circa 1825, occupation: cabinet maker, etc. & his household at Brock township, Durham County(Ontario North district), Ontario, Canada.
My Great-grandmother, Mary Ann Hartnett (Sep 23, 1845 - Oct 17, 1916) married July 29, 1867 in Port Hope, Ontario her first husband, Thomas Clouston. Thomas Clouston born: Ontario circa 1833, family origin: "Scotch", occupation: furrier, etc & his household are listed at Port Hope, Hope Township, Durham County, Ontario in the 1871 Ontario Census. They had 3 children, but unfortunately one child, Michael Alexander Clouston born Nov 13, 1869 died within the year prior to the 1871 census. Thomas Clouston died before 1875 in Port Hope. His widow remarried & moved to Kinmount, Ontario with their surviving two children.
I would appreciate any info you might have on Thomas Clouston's family & ancestry to pass on to my cousins. Please contact me by email to share research.