Artemis BJJ (MyGym), Can Sönmez, Bristol, UK - 30/03/2015
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.
Push off your leg and bridge back, 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 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. There are several options at this point. I like to either reach across their neck and grab the gi, or better, reach under their head, grip the far armpit then lock my shoulder into their head and shoulder. Either way, push off your free leg and turn to try and come on top. With your grip on the knee, stiff-arm so they can't lock their half-guard (if they do lock their half guard, this puts you in the opposite side half guard pass position, so proceed from there). Free your leg (pushing on their leg if you need to) and move into side control.
Teaching Notes: I've been off sick for a week with bronchitis (Chris kindly covered Wednesday, while the women's class and Thursday ran as open mat), which has been frustrating. As much as I wanted to get back on the mats, I forced myself to be sensible and took it easy, sticking with just teaching. This is the escape I rely on, probably too much as I don't have many other reliable options. I think I could structure the teaching better on this, perhaps also putting in more detail about clearing the legs.
I suggested stiff-arming their leg with your opposite arm to start with, but perhaps going with the instinctual near arm and then switching is easier (though it does add an additional step). I'll try that next time, or at least mention it as an option. Like before, people were also having some trouble clearing the arms if it was a tight grip. I want to come up with a drill for that motion, so that's something to play with at open mat.
There are a few methods for popping their hook free. I mentioned the basic one of pushing with the arm, though I normally avoid that as it can leave you vulnerable. My preference is either a twist of the hips to pop it off, or pushing with the opposite foot. Both of those can be easier said than done, as somebody who has good back control is hard to shift. I'd really like to get in more practice at escaping the back, making my enforced absence doubly annoying. Then again, I can always get people to start on my back at open mat, something I should do more often.