Everything's fine thanks johnno
I think I was lucky. I managed to "wrestle" it to the ground, which took some of the pace out of its fall. It was also set up on grass which had just been given a good sprinkling, so the ground was softer than concrete!
It was mostly my pride which was dented
But I certainly agree with Dave ... about that feeling you get when something like this happens. I think my crackers are still making their way back down to where they belong.