This must have happened fairly recently, but I noticed only after finding every
English word marked in red when composing emails. Apparently, enchant-2 does
not automatically install the hunspell backend despite one's locale setting
being set to en.GB. The voikko backend is installed, however, thus
automatically treating all spell-checking inputs as Finnish (and marking them
obviously). Manually installing enchant-2-backend-hunspell did the trick, since
the correct myspell dicts were already installed.