Maths explained it clearly 13 years ago.
S104(3) does not say that.
Please refer to TCGA92/S104(3) :
https://www.legislation.gov.uk/ukpga/1992/12/section/104/enacted :
"shares or securities of a company shall not be treated as being of the same class unless they are so treated by the practice of a recognised stock exchange or would be so treated if dealt with on a recognised stock exchange."
And also "CG50203 - Definitions: different classes of share" :
https://www.gov.uk/hmrc-internal-manuals/capital-gains-manual/cg50203
which quotes the above legislation :
"TCGA92/S104(3) provides `shares or securities of a company shall not be treated as being of the same class unless they are so treated by the practice of a recognised stock exchange or would be so treated if dealt with on a recognised stock exchange’.
A stock exchange lists shares or securities of the same class in a single listing. It is a question of fact whether the rules of a recognised stock exchange would list different types of share separately. If the shares are listed on a recognised stock exchange you should follow the practice of that stock exchange. If the shares are not listed you will need to consider the terms of the shares and apply stock exchange criteria to them. As a general rule, a stock exchange will treat shares as being of different classes, and list them separately, if they have different rights or other features which would affect their value. For example, partly paid shares would not be regarded as being of the same class as fully paid shares, see CG50207+. However, also see CG50207 if the balance of the subscription price is payable within six months of the issue of the shares."
I would agree with Maths interpretation personally but just wonder how HMRC would interpret it. I have indeed wrote to them but several weeks passed now, no reply yet.