Vintage possibly WWll Navy Blue wool undress jumper Sailor size small‎ (B7)

Vintage possibly WWll Navy Blue wool undress jumper Sailor size small (B7) I believe it’s WWll due to the research I have conducted but can not guarantee it is very old. The tag is faded so I can not see the actual size Please review the measurements Vintage possibly WWll good condition has minor separation in thread on the side see pics Made of dark blue 100% wool serge, loose fitting, open at the neck and with a square Sailor collar. The jumper has a front and back yoke with one welt style pocket outside on the left front The collar has two stars on the jumper flap and is trimmed with three white piping, each 3/16 inch wide and 3/16 inch apart with outer piping 1/4 inch from collar edge. Sleeves have two navy blue button fasteners on cuffs, trimmed with three piping of white tape, each piping 3/16 inch wide and 3/16 inch apart, centered horizontally on the cuff and blocked off each end by a perpendicular white stripe 3/16 inch wide, connecting the ends of the horizontal piping. Distance from outer edge of perpendicular stripe cuff's open end is approximately 1-3/8 inches. Buttons are 25-line, black, with anchors Used - Shows wear and yellowing on the stripes