Right, Robert has given this a miss, surprising as I was sure he was on the right track. It has been over 24hrs so time to move on.
This is yet another effort from Stampe/Vertongen/Renard - it's the SV18M, redesigned powerplant and tail unit amongst other things. Later altered yet again to a single-seater.
OH, please, but a glass of beer for anyone who can tell me how on earth anyone accessed the front cockpit of this machine !