"Duck Tape" as a brand name is indeed available in the UK, contrary to the information in s&r's Google trawl.
I have just this very afternoon finished taping down our speaker cables to the floor using so-called "Duck Tape", in preparation for the Xmas and New Year jollies.
However, I think that calling it "Duck Tape" is indeed a heinous aberration, and that it is better thought of as "Duct Tape", the true name ....