the G8 is the twoseat-version of the Mirage G (geométrique).
The immediate forerunner of Tornado had been the ill-fated AFVG, or Anglo-French Variable Geometry aircraft. This was cancelled due of political disputes (offcourse) and shortly after Dassault unveiled their variable sweep Mirage G, followed by the G8 in 1971. Neither entered production, but the series formed the basis of the proposed 'avion de combat future ACF', a large twin engined single seatmilti-role fighter with a fixed swept wing. Very agile its performances required a Vmax of mach 3, then later as the real world intruded, mach 2,7 and finally 2,5 ; and a combat ceiling of over 59,000ft. In the event the 'Super Mirage' proved unaffordable and was cancelled in dec 75.