The CBM IR is simply another way of obtaining an ICAO IR not unlike the unapproved IR of yesteryear. Why would you want to spend more money doing 55 hours when you can get it at 40 hours?
I would love to call the CAA to "enlighten" perhaps us all,
Considering a number of us spend a lot of time pointing out their errors, I doubt they are in a position to enlighten any of us!
They do indeed incorrectly annotate licences "CB-IR" but that is only one example of the many curious entries I have seen.