British LaTeX files with Emacs and Hunspell

Question

I am using Hunspell with Emacs. In my init.el I set the dictionary list as follow:

(setq ispell-local-dictionary-alist
      '(
        (nil       "[A-Za-z]" "[^A-Za-z]" "" nil ("-d" "en_US") nil utf-8)
        ("english" "[A-Za-z]" "[^A-Za-z]" "" nil ("-d" "en_GB") nil utf-8)))

If I spell check this TeX file:

\documentclass {paper}

\begin{document}
The word i.e. and contracted words aren't accepted. 
\end{document}

% Local IspellDict: english
# LocalWords: 

the words "i.e." and "aren't" are not recognized, as every word containing dots or single quotes. Setting OTHERCHARS in the dictionary list to "['.]" does not help.

Anyway, if I change the dictionary "en_GB" to "en_US", it works.

So it seems that the problem is in my dictionary. I downloaded it from the link:
http://en-gb.pyxidium.co.uk/dictionary/en_GB.zip found on the site: http://wiki.openoffice.org/wiki/Dictionaries .