(Well, I don't think pictures would have been appropriate.
But at least I can still ride with a sore face!)
I had one warning only: these pedestrians walking against traffic initially seemed to be unwilling to give right of way to me. Not that I forced the issue; I am always as genteel as possible to ped's. But since I had nowhere else to go, they were forced to move. I had slowed, but after they moved, I resumed some speed.
I heard later from the policewoman who took eyewitness accounts that two ped's actually stuck their arms out, but one withdrew it. When I went down, one of the group seemed to be stunned by what had happened. But in the policewoman's words, "The perpetrator had one more chance to redeem himself by stopping to help, which he did not do."
I have learned never to block such a move with a free arm. It causes immediate loss of control.
He is in worse shape than me. I won't keep this grudge inside me.