Dumping only variant languages

Hi Kevin-

I've scoured the doc and just can't figure this out...

I'm using the dump/expand commands in the format -

aspell --encoding="UTF-8" -l en dump master | aspell -l en expand | tr '
' '\n' > en.txt

- to dump the English dictionary.  This works fine.  The only problem is
that it dumps spellings for words in all regions (variants); it dumps GB
(e.g, colour) and US (e.g., color) spellings.

How can I dump the dictionary in just US or GB spelling?  I tried -

aspell --encoding="UTF-8" -l en_GB dump master | aspell -l en_GB expand
| tr ' ' '\n' > en_GB.txt

- but it says the language is not known because en_GB.dat is not found.
There is only an en.dat file that points to all the variants.

Is there a way to dump a list in just a variant's spelling?

Thanks