On perusing my boxes of "stamps to be sorted one day", I find the task not only unfinished but, indeed,
unstarted.
However... delving into the box I found no less than five of the 19p Nativity stamps from 1994 and can post a photo of the phosphor band (tag) in question. The five stamps I have all come from counter sheets and all have the band in the same position. I cannot comment on any differences in tagging position that may or may not exist on booklet stamps...

Should David Y's stamps vary significantly from the one pictured than it may be worth investigating or confirming.