Prof Alan H. Nelson of UC Berkeley has a website defending the orthodox authorship position here. On this page, he cites 8 contemporary Elizabethan documents as "witnesses" in order to demonstrate that William Shaxper the Stratford actor was known in his lifetime as the author of the Plays. He asserts that as at least some of the owners of these documents must have been in a position to know the truth, this proves that Shaxper wrote the works. I wrote to him to point out that he had overlooked a relevant contemporary document: the Northumberland Manuscript. On refreshing his memory by looking at it (here) he expressed the opinion in private email to me that this also proved his point, as above the names of the plays Richard II and III appear the words "William Shakespeare". Amazed by his myopia, I pointed out that, apart from the fact that the document belonged to Bacon and included both works by him and "Shakespeare", right next to these words are Francis Bacon's name, so that what it actually says of Richard II and III is that they are "By Mr Francis Bacon William Shakespeare". I asked him how he could explain the presence of Bacon's name in this provocative location if Bacon had nothing to do with the authorship of Shakespeare, as he claims. He replied that he had "no idea" why it should be there, but that he "didn't need to explain everything", even while he continues to assert on his website that Bacon had nothing to do with the Shakespeare works.
I invited him, if he truly believed that the Northumberland Manuscript could be cited as evidence for Shaxper's authorship, to post this as the ninth example to his witness page and be prepared to put on record publicly his privately expressed opininion that Northumberland supports the orthodox position. He wrote to me that he would do this as soon as he had some time. But as of this writing, months later, and despite a couple of friendly reminders, he has not yet done so. Why not write to him and ask why not?