Hi @sam,
Thanks for the tip! I am not the most prolific Querybuilder in the world, but this at least got me started, so with some effort I managed to get the results! Not in the prettiest of ways, but hey - works for me!
Thanks again!
(For those interested: grabbed the json straight from the DB, converted that to CSV and processed that in a spreadsheet. Clumsy, I know, but I got there.)