Artemis BJJ (MYGYM Bristol), Can Sönmez, Bristol, UK - 18/11/2015
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: This remains the standard escape I do and teach. I have been trying for a while to add something else that is a useful escape from the back, but so far this is the only one I've found to be reliable (though adding in a turtle escape works, as I've done this month). I'll be trying another one later in the week, perhaps putting in that scoop escape again later.
A detail I think I'll start adding is trapping their leg by putting your foot close to their leg after you step over, to prevent them re-establishing their hook. I also talked about bringing your weight up onto them with this technique, as you don't always have the luxury of locking in a cross-face.
However, that did mean several people were turning to top half guard instead. Which is ok, but not as good as top side control: emphasising that walk around would be worthwhile. In sparring, I was finding that the Marcelo style single hook can mess up this escape, so that's something to keep in mind