They were built in 1885 as 2-4-0T locomotives, but five were rebuilt in 1890 as 2-4-0tender locomotives for working express trains between Exeter and Plymouth. They comprised the first ten locomotives of Lot 64, the remainder of which comprised ten similar locomotive Nos. 3511 to 3520 built to the standard gauge. In 1892 the broad gauge was abandoned and the locomotives were all converted to standard gauge tender locomotives, becoming a part of the 3201 Class.