A correspondent writes to ask about a construction he came across in a Sherlock Holmes story, 'The Red-Headed League'. He noticed 'that on one occasion Watson adds suffix -s to the first person singular verb in the present simple tense'. Why, he asks, would an educated man use such a construction? Is he referring to himself in the third person?
This is the quotation: 'Spaulding, he came down into the office just this day eight weeks, with this very paper in his hand, and he says: "I wish to the Lord, Mr. Wilson, that I was a red-headed man." "Why that?" I asks.'
The story is being narrated by Dr Watson, but it's actually not Watson talking at this point. It's Wilson who's narrating. So the question is whether Wilson would be likely to use such a construction.
We are given the following description of him by Watson: 'Our visitor bore every mark of being an average comonplace British tradesman, obese, pompous, and slow.' We also learn that he began as a ship's carpenter and now works as a pawnbroker. So it seems quite in character that he should use such a form.
This isn't the third person, though. It's the first person with an -s ending - a widely used regional dialect feature in English, both in Victorian times and today, and common in local London speech, especially in narrative discourse. We also hear such forms as 'I goes', 'I sees', and so on. It's a dramatic use of the present tense in narrative. The rest of the time people say 'I asked', 'I observed', and suchlike.
Conan Doyle does use nonstandard speech in his writing - for example, John Rance's speech in 'A Study in Scarlet': 'I was a-strollin' down ... them two houses... won't have the drains seed to...' - though it's not his stylistic forte. I find the usages rather stilted and tokenistic. But there are only hints of demotic speech in 'The Red-Headed League'. Mr Wilson has a few colloquial turns of phrase typical of the businessman trying to rise in society, such as 'never was such a fellow for photography', 'as true as gospel', 'a pawnbroker's business is mostly done of an evening', '[he] took to coming in only once of a morning', 'he... would come cheap'. 'I asks' is a clear instance of a nonstandard usage, in this story, but it's the only example, and it does stick out like a linguistic sore thumb. Which, I suppose, is why my correspondent noticed it in the first place.