Thanks very much for the reply and the advice is appreciated : ' )
I had already called for an ambulance at this time!

The player was assessed in emergency (A & E) and discharged withour much except warnings re recovering from concussion...

I have seen nystagmus in patients before and this was not quite the same... more of an equal oscillation at a constant velocity unlike the drift/snap type of movements of nystagmus...

In Aussie rules they let players who have been knocked out to return to the pitch immediately if they meet particular criteria and show no clear signs that neuro damage has occurred...it is amazing how little evidence based info is available on concussion...

The group responsible for horse riding/jockeys here in the UK has been looking at the Aussie Rules stuff to help determine how long and under which circumstances players whould be taken off pitch.

So I guess I am interested in what this phenomenom might have been knowing that A & E did not seem concerned...

Good info with your post PhysioBob