Andy,
T225-1 has both spellings: Khedival / Khedivial
Here are the 5 possible Khedival / Khedivial backs (according to Adam W.'s book):
t2251b.jpg
(I do need a few Surbrug backs to complete my T225 Bat. Nelson run, but that's another storey !!)
Khedivial with stats Factory 57
Khedivial with stats Factory 348
Khedival no stats no Factory
Khedival no stats Factory 57
Khedival no stats Factory 348
T225-2 all are Khedivial Factory 348 backs:
t225cobb.jpg
(I only need Willetts to finish my T225-2 set, but that's another another storey !!!)
Quick search gives us this definition:
khedive [kɪˈdiːv]
n
(Historical Terms) the viceroy of Egypt under Ottoman suzerainty (1867-1914)
[from French khédive, from Turkish hidiv, from Persian khidīw prince]
khedival , khedivial adj
So both spellings seem to be acceptable.
My opinion is that Khedivial is the Company's name, and Khedival is an ultimate "mis-spelling." I'd hate to have been the guy who did the final sign off on the proof !!!
FUN set by the way !!!!!!!!!