Ahh, so is your point that Horsfield did leave the coach?
Because that is covered in Horsfield and Pope's recollection but that was after Gannon had already left the coach.
At no point did Gannon throw Horsfield off the coach; the Vale chairman asked Horsfield to leave the coach. This was after Horsfield confronted and assaulted Gannon on the coach (which he admitted to himself).
As I say, give the Geoff Horsfield episode of the Undr The Cosh podcast a listen. He talks in details about the entire incident, including the build-up to it on there and, despite it being his side of the story, still comes off as an absolute bell.