I can't find any of the family on the 1861 Census, possibly missed them but have found a marriage of John
Clarke and
Helen
Borland in
Girvan 1854. Two entries, one transcribed from the original record and the other a patron LDS submission. Two dates given June 4, 1854 LDS
June 14 1854 submission 7315813 which lists 50 Clarke's marriage or births in
Girvan.
Worthwhile to look through those entries for clues.
So whether the 1854 marriage is just prior to leaving
Scotland, or may be a miscopy. The possibilities are many, even that John was married previously.
Good luck with your search Sue,
Linda..