First open Champagne bottle and consume contents. Then re-fill with nitro-glycerine or similar clear explosive fluid. Bore hole through cork and insert electrical det. Replace cork. Run cable to secure firing point in Lympstone. Watch ceremony on TV and press tit at appropriate moment. Sorted, and so much more spectacular!
(Personally, I've always wondered why no one has ever thought to make shallow grooves around the outside of the bottle with a glass cutter before rigging it for the ceremonial breaking.)