Not Britannia Creek Glass, either (note the correct spelling). It seems the item of interest is dated 2003. Rob Knottenbelt stopped using the engraved BCG monogram shown by Ross some time in the early 1990s in favour of a pontil stamp. What's more, according to
his website he stopped blowing hot glass in 2000.
Here's an intriguing suggestion that is almost certainly a red herring - but in any case a wonderful collection of coincidences. Just 100 miles away from Knottenbelt's BCG=Britannia Creek Glass was another operation called BCG for Battery Creek Glass, operated by artist Allan Crynes. The mark of that studio is very similar to the OP's example, as can be seen in the attached photo. It consists of the initials BCG and a monogram of the artist's initials AC. What is that extra notation on the OP's specimen after the date?
As far as I know Allan Crynes only made slumped and kiln-cast items including pate de verre, not blown hot glass as in the OP's item. He also seems to have ceased glass making sometime in the 1990s and in any case well before 2003. I'm sure Ross knows more of the history, given that these places are almost in his back yard (within that 100-mile radius).
Trevor