In reply to Pinch'a'salt:
Yes, both the top and the bottom of the gully are easily accessible from the Grand Montets lift, so I can see that there sometimes can be clashes between skiers and climbers. We had talked to some experienced climbers and guides about this route before we went and none of them mentioned that there could be problems with skiers here. In guide books this route is also mentioned as a good winter route.
We had contact with the skiers for about 15 minutes before the cornice went down. We shouted and waved to get them to move. We had at least 1hr climbing left and wating in -20c for so long is probably not an option. There photo shoot was obviously very important, so they could not ski down the other side.
There is long between good protections in the lower part of the gully, so we had to climb with long rope. Our lead climber had 15m of rope out when the avalanche came – he bumped 30m down, so we were clearly very lucky to avoid any kind of physical injury or casualties.
I stil think that the skiers were extremely irresponsible, but it is not possible for me to change their attitude. I guess the only thing I can do to avoid incidents like this in the future, is avoiding routes there by any chance can be interfered by off piste skiers.