"It's a sonic screwdriver. Never fails. There we are. Neat isn't it? All done by sound waves."

Victor Pemberton, an actor, writer and script editor, wrote the Doctor Who Season 5 adventure, “Fury from the Deep”. In this story The Doctor uses a regular screwdriver to undo a bolt that was holding a sealed black box shut. This box was fitted to a gas pipe which led to a nearby Euro Sea Gas Refinery. However it was the production assistant, Michael E. Briant who suggested changing The Doctor's normal screwdriver into a "sonic" one while on location. Briant would later go on to direct future Doctor Who stories including “Colony In Space” and “Revenge of the Cybermen”. 

The very first physical representation of the tool now synonymous with Doctor Who was in actuality a simple life vest whistle. It is believed that after Patrick Troughton accidentally dropped the originally intended screwdriver prop down a pipe during rehearsal, he improvised and grabbed a whistle that was hanging from a costume and simply referred to that as their “sonic screwdriver”. And why not, the audience had no idea what a sonic screwdriver looked like and no one involved with the production had any inkling that this seemingly throw-away gadget reference would go on to become one of the most famous tools in all of science fiction. 

The exact model of vintage whistle used by the production was debated for many years by eagle-eyed Doctor Who fans, but ultimately was identified to be this specific design by collector Lee Moone. The original whistle prop is not believed to have been retained after filming and was most likely returned to the costume rack along with the life jacket it was attached to. And the original screwdriver prop was, as far as anyone knows, never recovered.