I can't tell what year your question was raised, only the month. I can, however, assure you that the young man in the photo is not wearing a Blair tartan. Other responders correctly state that this is a military uniform tartan, not a clan or family tartan. There are over 430 distinct Blair ancestral lines according to the Blair Society for Genealogical Research. Blair of Blair (of that Ilk) and Blair of Balthayock are apparently separate lines, both dating to the late 12th or early 13th centuries. At that time (medieval) there was no such thing as tartan to identify families (at least so far as the best research can discern). One responder correctly states that the use of tartan as we know it today to identify a particular clan or family dates back to the first quarter of the 19th Century,
The Clan Blair Society, based in the United States, takes its logo from a melding of the badges of Blair of Blair and Blair of Balthayock, and welcomes anyone with the surname Blair as well as anyone having a Blair ancestor. Their website is clanblair.org. A partner organization, the Blair Society for Genealogical Research, is perhaps the most important source of genealogical records specifically related to the Blair surname.