why does the TOG II* have an asterisk while no other tanks do?

The_Chieftain: The asterisk was the British Army's method of designating a 'variant'. Where the US does A1, A2, etc, or "Mod 1, Mod 2", the British put one or more asterisks if it is not sufficient of a change to warrant another mark number.   See, for example, their rifle, the Lee Enfield No 4. Mk 1 and No 4. Mk 1*. The only difference is a notch in the bolt track.