I dont know that there are any hard and fast rules to the Viceroy/Bell watches but for my own count i would have expected to see a Cal.12 inside this watch due to the 1-12 numerals on the hour register.
The Siffert i just displayed in the below Watchuwearing point has the 3,6,9,12 hour register, its these registers i associate with Cal.11 movements. That being said you cant imagine that the number of 3,6,9,12 register dials ran out at the Heuer production plant at exactly the same time as they ran out of Cal.11 movements. The obvious conclusion is that the must have been some exceptions to only 3,6,9,12 = Cal.11 rule.
Sorry to say but i beleive there will never come an absolute rule on this point.
Cheers - Darren

: Sorry, something went wrong - here is the photo...

: Is this correct for a Cal. 11...

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: Cheers
: Stewart