Chris,
Talking of keeping an eye open: I ventured into Top Shop's vintage concession this weekend, and I was amazed at how many early 80s pussy-bow blouses they had with what looks like the same label that's in your skirt - also a few 70s looking jackets with the larger label. I'll have to go in and check the modern label. On Ebay, you have to look carefully at what's available, as the more recent stuff is rather less thrilling. I'm wondering if the 'W' label was an extra line concurrent with the regular label...
L