you are correct.
aspell works and can check files from CL with the GB dictionary so I think it is a problem with abiword.
A further note to this. I did a bit of digging (found that I can use the GB dictionary under Zenwalk, just not Vector). It turns out that Abiword under Zenwalk is set to use the main dictionaries, but it uses its own dictionaries under Vector. Found and downloaded an english_GB dictionary, and it works now...
If anyone else wants languages other than US English, have a look here:http://www.abisource.com/download/abispell.phtml
The dictionaries all seem to be in Zip format, and should be unziped into /usr/share/Abisuite-2.4/dictionary. That, combined with having LANG set to the correct language seems to do the trick..