GCSE general question

[Flyingflit]

Just popped into my head reading another thread… with multiple exam papers (AQA, Edexcel etc) and different question sets, how are the grades levelled across all of them to give one set of final results?
Are they quality assured/levelled at time of paper setting, or as part of the marking, or something else does anyone know?
I get that overall marks are on a distribution curve, but is that done at a exam board level?
this is my third time going through GCSEs and I’ve only just considered it!

The exam boards send their proposed grade boundaries (with proportion of kids who will get each grade) with reasoning to Ofqual who either approve or reject. This is done once all the papers are marked - grade boundaries aren’t decided till then.

e.g. https://www.bbc.co.uk/news/education-21426396

No, this doesn't take place and some years there can be quite a big difference between the exam boards (eg in terms of the percentage of As and Astars awarded).

edited to add - I see that some more knowledgeable posters say it does happen, which is good. Although I don't understand why there is such a big difference in the proportions of each grade awarded then?

So once all papers for an assessment are marked by examiners + sampled by Chief Examiners, each assessment goes to Awarding Panel who decide grade boundaries. The grade boundaries are then applied and final grades are determined and released to centres + learners.
Ofqual have oversight of Awarding panels and will audit these.

Thanks for the replies, that’s really helpful, can’t believe I haven’t considered it before now.