I think I might've found what the mystery propeller mark is for at last.

Today at an auction viewing I saw the mark on a box set of glasses, my eyes lit up as I have a couple of vases somewhere around here with the same mark on the base.
This set was made by Cristal d'Arques.
Inside the box was the all important "with compliments..." card from a company called ScanDutch.

Their logo is the mystery propeller mark!
So presumably, they have commissioned these items to be made for them by Cristal d'Arques.
I know the mark has turned up on items by other companies, such as Skruf, so I'm guessing these too are commissioned items for ScanDutch.
I found this little bit of info about ScanDutch here:
http://www.flickr.com/photos/reinvented/3432226811/Dan