commenced a descending left turn to 200 ft amsl, approaching the display line at an angle
of about 45º. The aircraft then pitched up into a manoeuvre with both a vertical component
and roll to the left, becoming almost fully inverted at the apex of the manoeuvre at a height
of approximately 2,600 ft amsl.
It would appear that this is the key comment from the initial report. If I understand correctly, the loop was entered at around 200ft. I would ask those who know if that is within acceptable licensed parameters.