What is Watson's "old service" in "His Last Bow"?

Question

I’d like to ask about a sentence in "His Last Bow" by Arthur Conan Doyle.

As to you, Watson, you are joining us with your old service, as I understand, so London won’t be out of your way.

I can’t exactly tell what the speaker Holmes means by the line above, especially about his use of the word “service”. It certainly isn’t about military service, is it? So what’s this? They are taking a man to the Scotland Yard here, so is this “service” old friends in the police force like Lestrade, Hopkins and some others? (I don’t think they were there though, for the setting of this episode is way later than when Holmes was an active consulting detective in London) . Or maybe this “service” doesn’t refer to any organization or society, but a quality of someone’s character or something? By this line, is Holmes’ saying something like “you were a good sport, my devoted assistant, friend-helping guy, so of course you’re coming along with me like a good sport, your old self right?” I don’t know. Could someone paraphrase this please?

Answer 1

It transpires that part of the confusion with this sentence arises from a difference in the text between the first UK publication in the Strand magazine of September 1917 and the later collected stories as published in book form.

The Strand edition says (my emphasis)

'you are joining up with your old service'

The story takes place on the 2nd of July 1914, less than a week after the assassination of Archduke Ferdinand. Britain stood on the brink of officially declaring itself at War with Germany.

Dr Watson had been an Army Surgeon in India and in the second Anglo-Afghan war, so 'joining up with his old service' simply means rejoining the Army Medical Corps. he is likely doing this in anticipation of the army requiring the 'old hands' of wartime surgeons in view of what is to come.

Dr Watson's previous military attachment was to the 66th (Berkshire) Regiment of Foot, which by 1914 had been amalgamated into the Royal Berkshire Regiment who were garrisoned in Reading. As the story is set in either Suffolk or Essex (the lights of Harwich can be seen which limits the possibilities), Watson would be likely to go through London if he were headed there, hence Holmes' statement about London not being 'out of [his] way'.

The form of 'joining us with your old Service' has been continued into many editions, including the Gutenberg text, but on balance, the legibility and clear meaning of the original version gives no reason to suppose that the change from the Strand edition was intended to be a correction rather than a typographical error in its own right.

I am much indebted to Alexis Barquin at the Arthur Conan Doyle encyclopedia for a swift response to my enquiry on this matter and for their inclusion of the scan from the Strand Magazine.