Artemis BJJ (MYGYM Bristol), Can Sönmez, Bristol, UK - 24/04/2017
The first rule of the back position is protect your neck. There are lots of ways of doing that, but my preference is the Saulo Ribeiro method. One hand is in your opposite collar, the other hand floats, ready to block their incoming grips. Don't reach too far with that arm or you'll leave space: keep it near your chest. Your elbows are inside their knees, ready to pop off their hooks if the opportunity presents itself.
Next, bring your knee up on their choking arm side (so, the arm that is reaching over your shoulder and trying to wrap your neck, rather than the arm coming under your armpit). Angle your knee inwards, to prevent them from rolling you back the other way: they will find it easy to choke you if they can roll you in the direction of their choking arm. In one quick motion, move your head forwards and simultaneously shove their head sideways (this is presuming they know what they are doing and have their head tight to yours for control). Look towards them, keeping your head and neck firm in order to stop them moving their head back into place.
You can then continue, pushing off your leg, aiming to get your shoulders and spine to the mat. If you aren't able to get your head past theirs, still push off your leg. Put your head on the mat and then grind it underneath their head. This isn't pleasant for either of you, but it is generally effective: preferably you can get your head past theirs in the gentler method above. If they have moved you to the 'wrong' side, still get your head to the mat, but use that to bridge, then walk your feet back across.
When on the 'right' side (facing away from their choking arm), if you can, clamp your arm that is nearest the mat to your side, aiming to trap their arm. To really immobilise them, see if you can use that same arm to grab their opposite sleeve/wrist, meaning you're using one arm to control both of theirs. With your near arm, grab their trousers by their top leg (either by the knee or a bit lower). When you have the opportunity, switch to grip with the other hand. To deal with their hooking foot, twist your hips towards it to pop it off. If that doesn't work, reach your other foot over and push it off. There is also the option of pushing it off with your hand, but take care you don't expose your neck. Once the hook is off, immediately bring your same side foot over, heel tight to their shin. That should prevent them re-establishing their hook.
There are several options at this point. A simple one is to move into standard half guard, using their inclination to get to the mount against them. If you can, hook their leg with your leg, on the side you're moving away from. As they try to bring that leg over for mount, simply push it with your hands and turn on your side, moving into half guard. Make sure you get your legs above their knee, as otherwise you're essentially under half mount rather than in a half guard. If they are not trying to go to mount, you probably won't have the position for this transition, so in that situation I'd likely aim for one of the other variations, like going to side control.
Teaching Notes: I included a quick half guard drill, which refreshed the memory of those who have done it before, but I'm not sure it was enough to introduce it to people completely new to half guard. Hopefully it still helped: it looked as though they all had a handle on it by the end of the class. In terms of the technique, I also added in the switch from the 'wrong' side, as the move into half guard is so simple that I think it leaves enough room in the lesson. Emphasise things like hooking the leg, pushing the knee through far enough. A key thing to note is that it's intended for when your partner is trying to go to mount.