[GibbinR]

I've recently been puzzling away about the different punctuation conventions used in different editions of the same book, particularly with respect to quoting.
1. In some books, speech is surrounded by double quotes, and in others by single quotes.
As an example the Gutenberg 'Forsyte Saga' has double quotes, but both the Penguin paperback and the Kindle edition of the same book have single quotes.
When I first noticed this, a couple of years ago, I assumed that the Penguin compositors had just changed things to fit with their style guide, the same way that they seem to change 'em dash' into 'space, en dash, space', and 'semicolon, space' to 'space, semicolon, space'.
I also assumed that the Gutenberg was taken from an earlier edition, and that the Penguin compositors were probably just modernising in accordance with contemporary practice.
However I have recently been noticing that some fairly recent American editions of books also have double quotes. As an example I recently bought "The Book of The Ler" Kindle edition. a rather wonderful (IMHO) science fiction trilogy written from 1975-79 and recently republished by DAW, the original US publisher as an ebook. As it happens I also have the original paperbacks from the '70s. The first two volumes were published in Britain and have single quotes, the last volume I bought as an import and it has double quotes. The kindle edition, published in 2006 has double quotes throughout.
So I'm wondering if there is any general rule here. Is it the case that US practice is and always was double quotes, and British practice is and always was single quotes? Or could it be that 19th century practice was one way, and things gradually changed and at different rates in Britain and the US? Or is it just different by publishing house and even by book.
2. Actually, of course, to talk about which quotes get used is rather over-simplifying, because you do run across both inner and outer quotes. Working recently on 'The Golden Bowl' by Henry James, I became painfully aware of this. To give an example from fairly early in Chapter 1:
... "What do you mean, please, by my having 'done' with you?" ...
has both inner and outer quotes (as I think of them). So question 1 above really becomes 'single inside double' vs 'double inside single'.
However in some way that I can't quite properly articulate, there is another related punctuation difference that one sees, and this relates to whether related punctuation is included in the quotes or just outside it.
To give another example from 'The Golden Bowl' early in Chapter 1:
... poor Calderoni, fresh from Rome and now apparently in the wondrous situation of being "shown London," before promptly leaving it again...
In the Gutenberg text, shown above, there is a comma between 'London' and the closing quote. In both the Penguin Classics edition of 1966 and the Oxford World's Classics edition of 1983 or 1999 the comma comes after the closing quote (and in both these cases the quote is single):
... poor Calderoni, fresh from Rome and now apparently in the wondrous situation of being 'shown London', before promptly leaving it again...
I can't quite articulate it precisely but the latter case(s) only seem to happen when what is being quoted is a short phrase rather than a full sentence or reasonably large part of one. So for example from slightly later in 'The Golden Bowl' Chapter 1:
"Oh, you'll hear enough of it," she laughed, "before you've done with us."
has the punctuation inside the quotes in all three editions.
It also appears to me that related punctuation outside enclosing quotes only ever happens in books where the quote convention is single inside double, but I haven't spent much time checking this.

Now if any hardy souls are still reading this append, the reason for posing this problem is that like a lot of other people who add books to MobileRead, my basic source is Gutenberg, which is a collection of transcriptions of books mostly published in the USA.
Mostly what interests me are books written by English authors in the 19th and early 20th centuries, and I would like to restore them as far as possible to their original form. Most Gutenberg texts have outer double quotes, and related punctuation inside fragment quotes. I am increasingly suspecting that it would be more authentic (for English authors) to invert this to outer single quotes and related punctuation outside fragment quotes?