Moved to the Pub.
I done this yesterday, the first of three cubes from the kettle. As I was filling the second I noticed the bung on the first was leaking so I quickly went and cleaned a tap turning open and closed a few times whilst pouring boiling water through it. Put the cube on it's side replaced the bung with the tap flipped it up the right way, whoops tap is open. Then realised the second cube was overflowing. Hadn't even had a beer yet, which I took as being the problem and quickly rectified.