Voice and the Subjunctive

I was reading, entirely for pleasure, a 12+ fantasy recently. It's by a writer I know and respect and reading it was a thoroughly enjoyable experience. But you know how it is when you write as well as read, you can't help noticing how something is written at the same time as enjoying the end product. And, in this case, one little sentence stopped me in my tracks and kicked off my musings.

The sentence in quetion was direct speech and it went something like this: 'If I was to do that, then .....' Now, any good grammarian will tell you that the 'was' in that sentence is quite simply wrong. The sentence should go: 'If I were to do that, then.....' It's all a matter of understanding that you need to use the subjunctive mood in an if statement. For most of us, this is all Greek (or Latin) of course, but I suspect anyone with a finely tuned ear winces a bit when they hear 'was' instead of 'were'.

So I could just say: 'Bad bit of editing there. They should have corrected that.' But I'm not sure I'd be right. It's all a matter of 'voice' you see. The character in question is a mediaeval peasant. He has no education and he can't read or write. He's a country lad with no delusions. So would he use the subjunctive? I don't think so. And as the 'error' was in direct speech, it's exactly right for the voice.

Now this particular book was written in a close third person voice. But what if it had been written in first person? And what if the protagonist had thought that sentence? Would it still be right to use 'was'?

I know a lot of people will be saying so what at this. But it matters to me. I do have a finely tuned ear. I wince when people split infinitves (to boldly go) and I know the accepted wisdom is that this is OK. Heavens, I even have a problem with dangling prepositions (what we were looking for). Those might be pedantic, but using the subjunctive isn't. It's subtle, I agree, but it does change the meaning.

So where does that leave us writers? Are we true to voice, and gramatically incorrect? Or not?

I wish I had an answer.