Again on Sats it is a sound level 5 with possibilityl for high level in Maths, her class have recently been working on GCSE algebra which she handled well.
If she's stronger on the maths side, it might be worth mentioning this. (The implication is that VR may not have been a full reflection of her abilities - but don't go so far as to say that.)
Appreciate the point regarding the virus, in truth it will not have been the cause of the results but perhaps combined with natural anxiety and lack of sleep the night before all contributed to under performance, I also think she picked up hugely on my nerves for her but have been told that I should not mention this. School have given her a 1:1 and are doing what they can to support. My biggest worry is how to explain the results adequately when none of us understand them.
I think you may be putting too much pressure on yourself. Most appeals are probably decided by how the panel judge the evidence - what you say is unlikely to alter that. My advice is to mention extenuating circumstances only very briefly in the first instance because they're not particularly strong (you cannot easily prove nerves and sleeplessness, and cannot reverse a decision that the child was fit enough to attend school). Let the panel ask you questions if they wish (and they probably will), but if you yourself put the focus on extenuating circumstances there's a real risk they will come across as a bit lame, and sound as if you're struggling to find excuses.
I do of course appreciate that what you're struggling with is to understand what happened - but that's a point you can be honest about and put to the panel. Judging the impact of circumstances is no easy task for parent or panel! All you can do is hope that with such respectable 11+ scores they will take the view that you don't have too much to explain. The key is more likely to lie with the strength and range of the academic evidence.