Your main focus has to be your interpretation, not others. I got 20/20 for my Lear essay in the trials and it was marked by the Head of English who has also marked HSC, and I don't mention other people's interpretations at all. You basically just need your interpretation, and a couple of sentences perhaps from another one just backing up what you're saying. Like, "I see A1S1 as........ this is supported by Brook in his production where Lear is shown to be...." sort of thing. Do not base your essay on other people's interpretations, you will get fucked over big time! Your first priority is evidence from the text itself, and then you can support it a bit with a reference to a production.