Did you manage to find out more of the Rutan Model 91ML vis Chapmans's Lotus ELSA's? Later code named Mercury by Aviation composites Ltd.
I was the Chief Design Engineer at Aviation Composites Ltd. and helped build a Production model, based on the original moulds and Scaled Composites Rutan 91ML protototype. My good friend, Ivan Shaw was our Production Manager at the time.
I resigned from the Company in 1986 after some disagreement with Managing Director and the Certified Aircraft engineer hired by AC. Basically, I wanted to build an aircraft not a racing car, so enough said as to why I was not happy with the result.
The number 2 (I've no idea of the reg number) was test flown in Florida and later displayed in Oshkosh '86 I believe. There was work to modify it and fit a nortan Rotary engine.