The 'KJ' is the squadron code and the 'I' is the aircraft's identity within the squadron.
The roundel has a specific position on the fuselage as the primary identifier of the aircraft - ie.. 'It's one of ours'.
The positioning of the lettering is secondary and placement was commonly according to the remaining space available on the fuselage.
Changes in policy at the time or other reasons could account for the reversal, also.
The chaps on the Military Aviation forum would be able to explain it better than I've done, I'm sure.
You might like to post your question on there.
They'll probably even be able to tell you what specific aircraft those codes represented at what time.
The Aviation History and Nostalgia forum is also a very good source of info on such matters.
Hope that's a start for you.
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Last edited by Stanwell; 18th Jan 2016 at 08:01.