After Rex's steampipe began leaking one day and Frank had to take his train, The Small Controller began thinking they needed another engine and so he arranged for Jock to be built. When Jock first came out for testing he was still unnamed. Jock's paint colour reminded Douglas of his days on the Highland Railway and suggested the name "Jock" for the new engine. The Small Controller and Jock liked the name so it stuck. Later, he pulled a doubleheader with Mike.
- Built- 1976
- Designer- Ivan Farrier
- Builder- Arlesburgh Works
- Arrived on Sodor- 1976
- Original Railway- Arlesdale Railway