Here is this reference from The Repertorie of Records.
This is absolutely NOT an endorsement of all their claims. As far as I know most of their findings may be unsupportable. They claim to have found a great many significant letter and word counts in many books besides the many Shakespeare works. Many of their counts depend on a method of counting where ambiguity is present. It may still turn out that many of their claims, as far as the counts go, are accurate, which might be interesting in itself. My intent was not to assess their book but to look for good ideas. In any case there actually seems to be a reasonable justification for a “Kay” alphabet since there are reasonable clues to its existence. This is important because a discovered cipher alphabet, predicted to exist, is likely to be far more credible than a somewhat arbitrary one found by modern day decoders but without any reasonable basis to use it, other than finding that it provided reasonable solutions.
This Kay alphabet then would be:
A B C D E F G H I-J K L M N O P Q R S T U-V W X Y Z27 28 29 30 31 32 33 34 35 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
(The ‘&’ and ‘et’ would be considered as ‘null’ values in the system.)