The "Coffee Pots" were constructed and designed at Tidmouth by a young Sir Topham Hatt when he was an engineer to the Tidmouth, Knapford and Elsbridge Railway. They were designed as four small 0-4-0 tank engines with vertical boilers that were nicknamed "Coffee Pots". This was partly due to the fact they resembled coffee pots, and they were prone to cough up dirty brown water.