Hi! I know your expertise is WW1, but I don't know anyone with more military clothing knowledge, and I've been trying to find the meaning of the numbers/abbreviations on the inner pocket label of this morning tailcoat I got off ebay a while ago.
From what I've been able to gather so far:
The numbers/abbreviations is similar to some sort of post-WW2 army thing I came across while researching online, where they would put that sort of thing on those inner labels like that
Regarding the phone number, it looks to be around 1940s/50s perhaps?
Hey! It is most likely late 30s/1940’s morning coat purely by the look of the label alone. Moss Bros & Co Ltd. (as in MOSS, a suit shop and men’s formalwear in the UK for those who don’t know) during WW2 used this label on a lot of their officer garments as they also did produce uniforms and kit. There’s a chance the coat could be into the 50s, but just having seen that label before on the WW2 clothing, I’m willing to bet it’s probably 40s. It’s a pay to access thing to see the whole page, but there’s a newspaper advertisement from Jan 1940 placing Moss Bros & Co Ltd. in Covent Garden with the same telephone number although yes they appear to be reachable there into the 50s.
As for the numbers, they’re more than likely garment batch numbers, style or cut codes, and/or something used to identify the customer’s order as I don’t believe the UK used things like WPL and RN numbers which are for textile manufacturing in the US. I saw another one of their jackets with a written “A” followed by a string of five numbers and three more numbers much like your garment here on the same label, so this also isn’t likely to be something written by any subsequent sellers once the coat went into second-hand circulation. Not sure what the two standalone letters are, this is pure speculation, but if they are “MJ”, it could be the shop’s way of abbreviating the garment type “Morning Jacket”, could be initials, or just a part of the one of the codes mentioned above, but the paired letters like that I can’t seem to find on their other garment labels. A flight navigator’s blue tunic from WW2 had “BLT” written on his label from Moss Bros, didn’t match his initials, so unless he ordered a sandwich, it’s probably a garment abbreviation or a part of the item ID.
If this looks more familiar to anyone else though, definitely feel free to chime in of course!
As a bonus, here are a couple adverts I found as well from the 1920s, 40s, and 50s.
thank you so much!!!

























