I have just read the article in this weeks MCN, and Guy says he decided not to do the Senior after an incident on the Mountain.
He came up to what he thought was fog/mist and backed off. The bike then went into a slide and he put both feet down as he struggled to keep it upright. At Keppel gate he was shouting at the marshals to get some flags out as 'fog' was an oil mist, and in his words, 'there were about 20 bikes involved in a crash' ( this was the incident that lead to Alan Bonners death)
I dont remember that many bikes being involved reported previously?