Sir Paul Nurse (Pres Royal Society, I think) was talking about him on 'Today' this morning. He remembered Sir Patrick giving a lecture on stage, with a roving microphone. As he paced up and down, he got closer to the edge of the stage, until eventually he fell off, backwards, and disappeared. Sir Paul said "We couldn't see him, but we could still hear him".
He managed to crawl back onto the stage, and just kept going without missing a beat.
What a pro.....
If you want to hear it
BBC News - Today - Sir Paul Nurse: Patrick Moore was 'total enthusiast'
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