Previously known as The Robbers’ Retreat, this was first published in 1901 and 1906 in books of naval songs. It was recorded in 1953 from a group of fishermen at Cadgwith in Cornwall, and given the new name Cadgwith Anthem and the new back-story as an old Cornish fishermen’s song. It was re-published in 1966 in Canow Kernow, a book of Cornish songs and dances. The 1976 Steeleye Span version seems to be based on the 1966 publication. Cadgwith Anthem is still sung by fishermen in Cadgwith and of course is popular with choirs throughout Cornwall and further afield.
The reference to Kashmir or cashmere in the song is thought to refer to a breed of rose.
There are many many versions of Cadgwith Anthem on line, here are links to versions by Steeleye Span and one by Port Isaac’s Fisherman’s Friends.
Sources:
https://mudcat.org/thread.cfm?threadid=73318
https://mainlynorfolk.info/steeleye.span/songs/cadgwithanthem.html