Just found the Philips feature on a (then) upcoming auction:
ROLEX GMT-master, PRESENTED TO DEREK GARDNER BY SIR JACKIE STEWART
http://www.phillipswatches.com/rolex...ackie-stewart/
"The watch has an extraordinary history. As indicated by the engraving found on its caseback: "To Derek From Jackie With Thanks 1971", this watch was gifted to Derek Gardner by Jackie Stewart showing his personal appreciation for the truly amazing work he did."
From April 2016 - I wonder how much it went for?
Too much I bet.
What a great watch and story though.