After climbing twisted rib, the three of us decided to abseil down hairy gully. Since we climbed in three, 2 of us were at the bottom and our last to come down was preparing his set up. It was at this time two trainee instructors from a outdoor company who were under instruction from the company’s seniors decided they would set up a static rope for everyone to use. We thanked them etc, but they decided it was going up now. Although we told them several times our partner was just coming down hairy gully, and with both ropes of our abseil clearly visible, they decided "it’ll be fine" and soloed the climb, with our partner on his way down.

As communication is difficult at the crag we tried to let him know but he came down anyway. It could have been so much worse if the TI was knocked off the climb by our partner

and centres should really be monitoring groups behaviour.
Climbers need to have patience.
More common sense and etiquette needs to be taught