www.gov.uk/government/news/further-details-on-exams-and-grades-announced
Basically students will get grades based on their teacher’s predictions which will take into account mocks, coursework and prior attainment. The exam board will turn these predictions into grades (so they will look at how the entire year group has performed I suppose and put them on the usual curve).
Students will have a chance to appeal, and to take the exams when schools reopen or in summer 2021. All round the only real solution that could work, I think.