Merlin is based on the LSWR N15 Class, referred to as the "King Arthur" class by the Southern Railway, specifically No. 783 Sir Gillemere. In 1943, Sir Gillemere was fitted with three stovepipe chimneys by Oliver Bulleid as a wartime experiment. The way the smoke was spread out was meant to make the trains less visible to bombers overhead. The experiment wasn't a success, and the engine was quickly converted back to normal.
- Merlin will appear in the series soon.