Some of the different types of Y straps wartime and post war,most have no markings on them and were made by different makers who probably made the pannier bags,and used the canvas off cuts to make the Y straps.
Above and below a pair of probably wartime straps shown fitted to the pannier frames.
Below a long strap with unusual lines in the canvas,have seen the same lines on wartime pannier bag canvas.
Below a short strap which is odd in that it has a brass buckle,but fitting on the webbing are steel.
Below another short strap,with odd coloured webbing straps sewn into a dark green canvas.
Below a long srap , most probably wartime with brown canvas.
Below a pair of straps with all steel fittings,these are probably later war time.
Below some cut straps,probably wartime with the line in the canvas.
Part two as all the pictures got mixed up.
Below Canadian post war straps,made with a dark green coloured canvas.
Below a pair of straps made with leather instead of canvas,the makers stamp on the webbing strap is probably the webbing maker rather than the Y strap maker.
The lines in the canvas are the makers mark used to identify the canvas
I made brass & asbestos insertion cotton muffler bags for ships while at uni and asbestos impregnated stitched & glued pipe lagging & stuffing gland packing
The different grades of canvas had different patterned lines in different thicknesses and different distances apart
Like tubing this has to happen because once you start to cut the roll or bolt you loose the ID of what it was
Same story of course for the parts cut out and the lines also show the direction of weave as they ran down the middle of most rolls .
Just like the pannier frames and the pannier bags, the Y straps were produced by many different factories. And each factory had its own interpretation, added its own details. We find the same variations in the pannier frames and in the pannier bags. Would be interesting to make a survey of these too...