Well, the '23 roster is known to have errors in the RGS engine list. Doesn't include engines known to be on the property, includes ones probably gone by then. For ex: Class 60 engines listed for RGS are 3, 6, 10, 13, 15-19 & 21. However 12 was around until '42 and 13, 18, 19 & 21 were, according to other records, scrapped in 1916!
As I noted, the person/people who made the roster seem to have used the then current numbers for the Class 70 engines, it seems they were unaware of the changes due to engines that spent the 1890's as std ga.!
hank