Quite correct, no evidence so far on any series 1 vehicles, in fact the army museum bandiana was somewhat in the dark about the origin of the series 1 ceremonials for a time as well because they were among much later vehicles in the arn sequence (ex commonwealth fleet vehicles given to the army later on).
Given that the ARN ledgers stretch to before land rover production began the evidence would be there. Granted we haven't cataloged the entire arn sequence, but we have done some pretty big sections, and continue to expand it day by day.