This technique is used against a straight punch.
As your attacker throw the punch, block it with a basic inside forearm block and step forward with your left foot.
Twist anti-clockwise on the ball of your left foot and take your right arm behind your attackers back. Place both of your feet together.
Bend your knees and lean forward slightly to pull your attacker onto your back.
Straighten your legs to lift your attacker off the ground ready for the throw.
Take your head down to your left knee to throw your attacker off your back.
Strike with a right handed palm-heel to your attackers right shoulder. Take your left arm round the back of your attackers right arm and hold your right wrist as shown.
Place both knees on your attacker and raise your hips to apply the shoulder arm-lock.