While sometimes, especially in the earlier period for the records mentioned above there can be an occasional legacy from Secretary Hand, especially in the earlier records, the confusion more often derives from a more personal, sometimes quite ideosyncratic approach to the forming of capital letters by the gentlemen concerned
Based on many years experience, I've compiled the following list.
Note that much depends on the particular hand of the enumerator or the registrar as to which possibilities can be confused. In census enumeration books, statutory registers, OPRs, and other contemporaneous reocrds, study of other pages and records is well worthwhile and highly recommended.
The following confusion in interpretation can easily take place.
L/S and the reverse
D/P and the reverse
I/J and the reverse
M/N/T and the reverse
H/K/F and the reverse
U/V and the reverse
M/W and the reverse
R/P and the reverse
Q/L and the reverse
I as G
P as G
G as Cr or Ci
As or Ar as Ch
Ag as Cl
Cl as A
St as H
Your comments on the above in terms of your own experience greatly appreciated, especially in terms of omissions.
David