The following is from the book I quoted above and regarding the time of issue for 1914 Stars.
Three different styles of naming have been observed, yours looks to me as if itís the first style, the characteristics are slightly uneven, letters 2mm high and lines 3mm apart. If it is the first style of naming then the majority were issued in 1919 and 1920 so the envelope possibly (but maybe not) held the pair as well as his clasp and roses issued in 1923? 1914 Stars issued in 1923 and later have 1.7mm high letters, are evenly impressed with slight variations, full stops, commas and colons, although it isnít a hard and fast rule.
I reckon the best way to judge the year of issue for the Star (if you really want to) is to measure the height of the letters (2mm or 1.7mm) and then do eeny meeny miny moe
The book also states two kinds of bar were submitted for production, a sew on and a slider. The sew on bar was chosen as it was 50% cheaper to produce.