Working Instructions. Wireless Remote Control Units H (S.R.D.E). WO 1042 - Engeland Voorschrift Working Instructions. Wireless Sets no.18, Mark I, Mark II and Mark III - Engeland Voorschrift Fitting Instructions. Wireless Sets no.19, in Cars, 5 CWT. 4x4, S.R.D.E. - Engeland Voorschrift