I am little perplexed by a theory of my friend's...
She thinks that examiners tend to add up your marks to see what you get in a practical exam, and if you're a few marks off, say, Merit, and they think you deserve Merit, they tweak the marks a little so that they make 120. This happened to me in an exam once where I played the scales really badly but somehow ended up with 17 so that it added up to 130...
This friend once said that she had just got a Merit in her grade 5 viola with 120- and she could see the examiner's rubbing out on the mark form, adding on a couple of marks so that it added up.
Has anyone else found this? Is my friend right?

It only happens in the case of 99,119 and 129 - a single mark will be taken away or added depending on whether the performance deserved it. Most examiners seem to consider anything that's 1 mark off a pass, merit or distinction to be cruel.

Well ............. I have a hunch that if you get, say, 119 and the examiner feels that overall the performance was worth a merit, he / she might look for something that could be tweaked. But I must stress that it's only a hunch, and that I have absolutely no basis for believing that to be the case.

There used to be a rumour circulating that they did not award scores of 99, 119 or 129. However, I know that 's not the case, as I have heard of people getting these scores (although not any of my students, to date.)

Maggie