Bosch magnetos were used quite extensively on the very early models, my 1911 model has one but EIC (Euston Ignition Company) only came into being at the instigation of the British Government when the supplies of Bosch equipment ceased at the commencement of the First World War. Once stocks became exhausted magnetos became a critical item as very many vehicles used this form of ignition and existing British manufacturers could not fill the gap. It would be unusual to have had a Bosch magneto fitted as original equipment as late as 1918. As they are interchangeable, (quite deliberate) a magneto from an earlier model could have been fitted to the 1918 engine. Another magneto I have seen on early machines was "Dixie" which I believe came from America, Thompson Bennett was also used by Douglas as one of their Magnetos of "First class British make". CAV magnetos were sometimes used as an alternative to EIC on 4 hp models. I have never seen one as original equipment on a 2.3/4hp. BTH is very much more common in the 1930s with Lucas in the late 30s. 40s and early 50s before finally a Miller alternator system on the Dragonfly.