nothing to be proud of, but first kilted scuffle

[gilmore]

You responded appropriately. You stayed calm and in control, and you used just enough force to get the point across.

...

Where did you go to law school?

Sorry, but on the facts given, our friend could easily be found guilty of battery, if they were established in court.

Force can be used only to resist an attack on one's own or another's person. There must be impending peril of unlawful force without convenient or reasonable mode of escape, and there must be a reasonable belief of immediate danger.

According to the facts set out, there was no threat of immediate physical danger, nor was leaving the scene at all impossible.

Further, only as much force as is reasonably required may be lawfully used. E.g., the use of deadly force against non-deadly force does not constitute a defense of self defense. In other words I doubt that neither the mere tugging of a sporran belt ---having already been done---nor even the threat of one's sporran belt being tugged again (which was not in the facts given), would legally justify knocking some one to the ground.