I am surprised that no one has posted any comment on this subject, surely one of the most startling and controversial incidents to strike Isle of Man racing on the Mountain Course.
Obviously, we must grieve the two fatal accidents, and we must send every best wish to Steve Mercer, and pray that he makes a full recovery.
However, when you consider that the entire Mountain Course is marshalled using ( I presume), high tech Tetra radios, it seems beyond comprehension that there should be a breakdown in communication in a way that could cause such a catastrophe.
Even allowing for the first mistake, i.e. a Marshal sending off Steve and others without the escort of a Travelling Marshal, you would think that other Marshals, and the Clerk of the Course would have cottoned on that something was amiss. I am guessing that Steve will have travelled about six miles to Ballacrye, so probably around four minutes passed from their departure before Steve arrived at Ballacrye
Furthermore, I am surprised that the driver of the car has not been named, or the police officer occupants. It always makes me think that there must be some underlying reason for this lack of information, that we are not being told.
I should point out, that I am aware there must have been certain officials in a state of shock as the news of Dan's accident filtered through, and I accept that this could have had some bearing on the chain of events in the immediate moments afterwards. 

Finally, in the event of another serious accident in the future, which causes a red flag. It seems inevitable that the road closure at the scene of an accident would remain in force for some time. I cannot think that riders will be expected to remain on the course until the road re-opens. Imagine an accident at the Verandah, or a similar spot, in evening practice. The weather closes in, it's getting dark. Meanwhile, the road remains closed for investigations to take place. What will be the procedure to get riders back if there is no travelling in the reverse direction? I cannot think that any riders will accept being stuck on the side of the Mountain until the road reopens.