Simplex 40hp petrol locomotive as used on War Department Light Railways - there were three degrees of protection, open ones (ie no armour whatsoever), protected (as seen) and armoured, which looked a bit like a tank. The protected and armoured ones earned the nickname 'Tin Turtle' for obvious reasons. This one's been regauged from standard gauge (that used on normal British railways) to 2 foot gauge as commonly used by the WDLR.