This song like some of his other compositions is worth studying from the point of view of writing songs.
He is writing from personal experience, this was a factor in success of the radio ballads too EXAMPLE using voices of fishermen in Singing the Fishing, Wqrds and phrases were used like that in Shoals of Herring, So Ewan had never been a fisherman but the song becomes convincing because he listened to the words phrases and the speech rhythms of Sam Larner and others and it became the song.