At the moment there are 49 on the Registry master list, which is updated constantly.
There is a simple explanation for the "discrepancy" reported in this thread.
The Charlton census figures were obtained from the master list, as it stood at the time.
The published version of the CPMS Registry was last updated in early 2016.
The 30th edition GPM was completed in the late summer of 2017, leaving a year and a half roughly for additional notes to be recorded.
Such a note was 33000133124 mentioned below, which was in the Coin Expo sale, April 2016 - too late for the Registry but in lots of time for the catalogue.
Other recent additions have come from the 2017 Coin Expo (Bell) sale (33000253751) and of course 33000466746 from this very Forum, both of which were seen too late for the 31st edition.
The new high number was missed and will be forwarded to Charlton Press for the 31st.
I anticipate the 4th ed. Registry should come out in approximately one year, as we have been doing triennial updates.