The old printer's rule about punctuation inside the quotes was basically "for appearance." If outside, the punctuation looks a "bit detached".
However, the Oxford Guide to Style (aka Hart's Rules for Compositors) states that the punctuation in British practice goes inside or outside the quotes according to sense, but if the same mark is logically required both inside and outside (typically, when the quote ends with a full stop), then it is not repeated outside. It goes on to say that in US practice, the mark is always inside the quotes, and this can give rise to editing problems when combining US and British sourced material.
Examples of British practice quoted from the above cited book:
They were called 'the Boys from Dover', I am told.
She was heard to mutter, 'Did you do it?' (omit full stop at end of main sentence)
Can you verify that he said, 'There is only one key'? (omit full stop at end of quote)
Did he really shout 'Stop thief!'? (both marks serve a purpose)
He concluded that 'We must give up the task.' (omit outer full stop rather than duplicate it)
Cogito, ergo sum means 'I think, therefore I am'. (the quote is a specimen not a sentence, so has no stop itself)
Oh, and welcome. I'm rather liable to erupt in explanations like that...