Royale Studios 17 - Two Mysteries Solved - Part 4

In my previous post I suggested that the catalogue label 'FJSS' stood for 'Fred and John' the names of the two models. The 'SS' I suspect is simply Soldier-Sailor. This is not just a wild guess. Royale advertisements which I have do mention a Soldier-Sailor set (without showing a sample picture unfortunately). Connoisseurs will also know that there are other Royale pictures circulating on the the internet using this label but they are from a different set 'Unapproved School', you will probably recognise the one below. 
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from Royale Studio's - “Unapproved School”
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You can immediately see a striking similarity to the uniforms used in the FJSS set, (sample below) and the soldier is clearly Fred Collins once again.
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Does this mean the two sets are linked? 
And what about the EX2 bit? 
More next time in Part 5.
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For earlier articles in this series click on the GIU/Royale label below