Daphne, in her 1970 essay on John Oram, wrote:
Prof. Moody of Trinity College Dublin informs me that “Rockite” was a name used to describe one of the many agrarian secret societies that flourished in Ireland in the 19th century. A Rockite letter was a method of seeking to intimidate a landlord or someone employed by or co-operating with a landlord, whom the Rockites had marked out for hostile attention.