High-intensity stuff - you plough through a couple of banker's boxes of files, looking for the nuggets of fact buried in the mountains of opinion, bluster, hysteria, accusations and counter-accusations, then you find a few reasonably clear things on which you can base a professional opinion, and from them construct an argument as to the balance of probability as to what is/has been happening.
All of this happens under the constraints of CPR Part 35:
(1) It is the duty of experts to help the court on matters within their expertise.
So clients might possibly pay someone for the privilege of destroying their argument. That doesn't look to be happening in this case, though I am not finding myself in support of all of it either.