I think you might be fishing in an unstocked pond there Trainlover222.
Official records (ie - recorded properly by the authorities - and not just from a wristwatch between two mile/km pegs, which may not even be accurately placed) would be few.
Unofficial ones are just word of mouth, and the speed tends to increase with each retelling of the tale.
I agree totally the so called speed records are blurred some what
I did read an article somewhere long ago about the XPT in southern NSW. They recorded it's speed using a police hand held radar gun at a level crossing.
Official Speed records require a complex set of conditions, as an example I was once involved in official speed trials for power boats conducted by the Australian Power Boat Association.
The course is a measured 1000m (required qualified surveyor's certification!) The boat is required to make a pass of the course in BOTH directions.
The run is timed in the following manner, two stop watches ( a & b) are started when the boat enters the course from one end, then at the other end when the boat exits the marked course two more stop watches are started (c & d), the boat then is allowed a maximum of 5 minutes to turn around and make a return run in the opposite direction.
As the boat passes the course marker watches c & d at stopped and recorded, then as the boat exits the course (original start marker) watches a & b are stopped.
Then you average watches a & b to get total time, average watches c & d to get the turn around time, Turn around time is then deducted from total time and the result is divided by 2 to give a time for the base 1,000m and hence calculated to give a speed in kph.
So an official speed record is NOT a simple matter of looking at a speedometer for a few moments!