At least in some years, the label was attached to the frame before it went on the assembly line - what, if anything, was stamped on it at that time is unknown as far as I know.
Look carefully at the picture here: https://andover-norton.co.uk/en/service/ Clearly, the label is on and the bearings are installed and the frames are not on the assembly line yet.
Norton changed the content of the dispatch records multiple times and on the more complete records, the date on the label matches nothing, for instance: 320691 - Batch No.: 64A, Frame No.: 114572, Date Off Track: 23 Oct 74, Date Passed Test: 5 Nov 74, Date Packed: 11 Nov 74, Date Despatched: 26 Nov 74 to USA the label has 7 1974 so it clearly was stamped long before being finished and it was clearly not on the assembly line for two months. It may have failed the test and then re-entered test once they got around to fixing it. Others in that year were off track, tested, packed and shipped in a day or two. Interestingly, in Aug and Sep 1974, the records were like: Date Built: Aug 26, 1974, Date Dispatched: Aug 26, 1974, MK2, Batch: 384 Note "Date Built" rather than any of the other terms in the record - unfortunately, I don't know the label date for any bikes of this type.
