Thank you for your translation efforts. However, it looks like you took the en-GB files from one of the Beta versions, which are partially obsolete by now. (You can use them of course if you are still playing with an old Beta).
I did a german translation in early April too, but then decided to stop working on it until i.e. the second Release Candidate becomes available in order to avoid unnecessary work. The en-GB files were and are still beeing changed several times a week (approximately 80 times since Beta3).
At present the backend en-GB in the SVN trunk is 1571 lines long (compared to your 2863), so unfortunately some of you work is already obsolete, too.
If you are interested, send me a private message with your email address and I will email the current en-GB files.
BTW - did you read this already:
http://dev.virtuemart.net/projects/virtuemart/wiki/Writing_translation