Urban myth I'm afraid .... reported over the years from many places.
I believe so.
However, it is such a good tale that I didn't want to say.
[serious]
As always there is a thread of truth to it.
When they had Phantoms at RAF Leuchars, they would often show a warning on approach to the airfield when there was a speed trap on the road to St Andrews (plenty of revenue from speeding golfers).
The rest is just imaginative embroidery as far as I know. [/serious]