Thought I'd try to describe a set up from a variation of the London I've come up with. Maybe you guys have been doing it, maybe it's new to you. I figured I'd post and get feedback.
I haven't seen the new book on rubber guard so if it's in there, sorry, it's purely coincidence. I don't get on the mats very often these days and I see no point in keeping moves and ideas to myself. lol Hopefully I am able to explain this decently in words with no pictures.
Ok, so let's say we've got the london and we've got the opponents right arm trapped. You take your right arm and reach up DEEP into your own left leg. You want to act like you're trying to get the inside (opposite) of your right elbow up into the inside of your left knee. You're basically going to cup your outer left thigh (right about where you don't want to get thai kicked) with your right hand. This still keeps the opponents right arm trapped snug, and now your LEFT arm is COMPLETELY FREE. So essentially, you have the London position without having to use both hands. It takes very little flexibility from my experience. You want to get as sideways as possible and if you can do that, your opponent will naturally tilt a bit forward. Getting sideways is obviously key but it's not hard to do. You can hold the london the regular way with two hands, use the elbow to push the face a little and you'll get sideways. The omoplata/gogoplata is all still there, the triangle is still there is they fuck up with their left arm positioning...but whats new to me is that with your left arm completely free, you can pretty easily take your opponents right wrist and and set up a kimura. Hopefully you're able to visualize it. Grip the wrist with your left hand and push it back, just reset your right arm (at this point it's still tucked under your own leg, so just remove it) and lock in the kimura. Also, the omoplata is still right there for the taking as well. Works pretty well.
Looking fwd to hearing your thoughts and also how all the other forum members do trying it out. I first started doing this about 2 years ago but injuries and pure laziness have just kept me off the mat so admittedly, I haven't really refined it much. I believe it's a pretty legit, solid technique though and worth experimenting with. thanks for reading.