It is difficult to identify bagpipes without a maker's stamp being present or other compelling information or documentation.  Still, we are able to draw comparisons with known J & R Glen Bagpipes and follow them down through the ages. 

I'll start with this images (to the right) of a very early J & R Glen bagpipe that is stamped just above the ferrule bead.  Note the perfect beading and combing.
This is an outstanding example of their work.  The bagpipe is cocus wood with brass caps and ferrules and horn projecting mounts.  This bagpipe is likely ca 1890.  I get the impression that it was made for middle-eastern royalty. 
This is quite interesting.  The tenor bottoms had or have a partial brass sleeve insert.  In the top picture you can see how the bore was counter-bored to accommodate the insert.  Of course, it loosened and became lost over the years.
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The fit was perfect and invisible to the eye.  Because of the significant additional work involved special circumstances must have necessitated this sleeving.
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An example (above) of keyed brass inserts. They may have saved the wood from insects however brass and wood do not move in concert during temperature changes.
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Two-piece projecting mount made of ivory.
Regardless of the era, the care and attention to detail in J & R Glen bagpipes can't be criticized. The overal styling could be called "elegant". The beading and combing is perfect. I think that it was remarkable that they were able to maintain their quality over such a long period of time. I think it speaks to the strength of character of the founders and the overall commitment to quality that was passed down through the years.
Here's a newspaper clipping courtesy of Ron Abbott.  He too used to work at the shop as a boy, mostly hemping bagpipes.  The picture at the bottom is of Gordon Stobo. Allan Stark worked for the company prior to WWI. After the war he returned until WWII put him back in the service of his country. Following WWII he left to start his own company.
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