This is going to be short and sweet because, clearly, there isn’t a huge amount one can say about a drinking receptacle with the insignia of the Royal Army Medical Corps (RAMC) on it.
That it is special to John is in no doubt – he has it with him in a bedsit that is otherwise devoid of any personality whatsoever, he takes it with him to 221B, and he uses it often – but why it is special to him is never explicitly stated.
Its presence is generally held up as proof that John served in the RAMC – even Sherlockology state that it was his old unit (and no, the RAMC is not a unit, it is a corps, there are units within that corps but the RAMC as a whole IS NOT a unit – but that’s not what this meta is about so I’ll shut up now) in their props section here. Taken alongside John’s acceptance of the term ‘Army Doctor’ each time Sherlock applies it to him, assuming that mug insignia is from the Corps he served in does make a certain amount of sense. In fact, if Sherlock’s repeated use of the term and the mug were the only nods to John’s military career we got to see in the series then I’d accept that he was an officer in the RAMC without question.
However I have two issues with doing so:
1) It isn’t the only evidence. We have a wealth of other things to consider, many of which offer far more genuine insight into John’s army career than an incidental item of crockery.
2) I own several mugs with different army insignia on them and I’m damn sure I’ve never served in the Royal Irish, the RAMC, or the Special Air Service!
Facetiousness aside, the point I’m trying to make is that the ownership of army memorabilia doesn’t make you a member of the regiment/corps depicted on said items. The only thing you can reliable deduce from it is that the owner of the memorabilia has a reason for wanting a reminder of that regiment/corps in their everyday life. Personally I have a soft spot for the Royal Irish as I know quite a few of the men who served/are serving in that regiment, I have an RAMC mug because I wanted a “John mug”, and I was bought the SAS one as a joke after I spent an entire evening with a friend dissecting the plots of various Ultimate Force episodes.
Thus, as far as I’m concerned, the mug is not proof that John served in the RAMC. It may, possibly, be taken as circumstantial evidence that he did but I think it probably has a very different providence:
If I had to guess, I’d say it was either:
a) a gift from Bill Murray – the nurse who saved his life and with whom John is still in contact – to remind John just whom he owes a lot of pints, or
b) a gift from the Combat Medic who was embedded in John’s platoon on the front line, given as a thank you for John helping him to save several of their comrades after a particularly bad fire fight or I.E.D incident. A sort of, “yeah, you’re an honorary one of us” gift that John treasures all the more because it reminds him of who else is no longer serving Queen and country.
Or something along those lines at least. I hope it goes without saying that I’d love to hear your views on how John came into possession of the mug and what you all think it means to him.
I must also say that, despite the fact that in my head-canon John wasn’t a member of the Corps, the RAMC have a proud history and John, had he joined the Army as a doctor, would have found a loyal family with whom to serve. If you want to know more about the Corps, its history and its structure, I’m currently working on a companion post which will also explain why ACD’s Watson could be an Army Doctor and a Captain of the 5thNorthumberland Fusiliers but why modern day John can’t (and no, it’s not just because 5th Northumberland Fusiliers don’t exist any more).