Many years ago there was a film clip of the BBC getting things a little wrong when they wanted to blow up a piano - the first explosion made the piano fall apart but it wasn't very dramatic, so they tried it again, this time adding some flour which was supposed to puff out and make it look more impressive. What actually happened was that the explosively dispersed flour also burned, adding a few pounds of fuel-air explosion to the miss. The piano was blown to smithereens sending fragments many yards in all directions.
I have an idea that this was for one of Michael Bentine's shows, either that or Spike Milligan. It's been shown a few times on blooper shows.
Can anyone point me at a video clip of the explosion? Or does anyone have it in a form we can convert to a video clip? We need it for science lessons!