Grade boundaries are numbers out of top marks e.g. 80/160 was boundary for grade 4 English Language in November resits so 50%. The same grade boundary was 72/160 in June 2017 so a whole 8 marks different. These boundaries are, however, set on a bell curve so the same percentage of students will achieve each grade across the nationwide cohort.
There are no UMS marks with the new system afaik. Points/marks out of max. were only available to exams officers and teachers for AQA last year which made it impossible to tell where new retake students were within the grade they were awarded, unless schools were willing to help.
It's a bit of a faff for teachers to look up, especially when the website is busy, but it's possible.
So, for a student moving from school to college with a grade below 4 in English and/or it's very useful for the college department to have that number. A student who was very close to the target grade 4/5 at school may be automatically entered for the Nov resit at college and would probably be offered extra coaching and revision.
Some schools will accept ex pupils for Nov resits, but not all of them, so that's worth asking about too. I think some don't see the point as it doesn't show in their results.
Also, for new college students who may be offered Nov resit at college (English Lang) it's very important to note which board and the grade - Pass. Merit. Distinction - for the NEA (non-exam assessment) speaking and listening element as this can be carried forward. Thus, leaving valuable time between Sept and first week of Nov for targeted tuition and revision.