The Jock Scott is a dress salmon fly created in 1850 by John (Jock) Scott, born at Branxholm in Roxburghshire in 1817.
The Jock Scott has been used as a metaphor for fly fishing in general. The protagonist of The Edwardians by Vita Sackville-West is described as follows at the coronation of George V: "He was bored, he was disgusted; he wished that he might be casting a Jock Scott into the Tay."
References
Jock Scott fly Wikipedia(Text) CC BY-SA