It is a common misconception that the Douglas Engineering Company was the only company to use the fore-and-aft flat-twin. Douglas was the most prominent proponent of this engine layout, using them from 1907 until the outbreak of WW2, but they were not alone.
William and Edwin Douglas got into the motorcycle business by accident, when a company they supplied castings to, Light Motors, went into receivership. Light Motors were probably the pioneers of fore-and-aft flat twins. The Douglas brothers spotted an opportunity to carry on production of these smooth, nimble, sturdy, low-vibration machines, which performed well and seemed to sell. Their appeal was enhanced with success on the Isle of Man, European race tracks, dirt tracks, and as dispatch rider mounts in WW1.
So it is not surprising that a…