As I recall Terry Doe never explained the reason why a standard pellet could not be used. Perhaps it would have been better if he had then we could have all understood. The statement was thrown out because others had voiced an opinion for a standard pellet.
Now why it would be better for us not to have a "Standard Test" I don't know but would be interested in why legal advice was that it would be to our benefit.
The current situation is that there is no standard test and private forensic test labs can use any methods they wish. The Forensic Science Service criteria is that as long as these labs follow their own procedures then that's fine. How that helps us I don't know. The tester for one lab (Key Forensics) actually stated in Court that his job was to prove the rifle in question could shoot over power.
Terry is quite fond of making these statements but they are usually followed by no justification or explanation, we just have to believe him.
I have his number, we don't talk.