The grade boundaries for the new Edexcel A-level Maths exams taken in June 2018 were as follows:
Qualification | A* | A | B | C | D | E |
A-Level Maths (300) | 229 | 184 | 155 | 126 | 98 | 70 |
76% | 61% | 52% | 42% | 33% | 23% |
There is of course no guarantee that these will be a good guide to the grade boundaries for the 2019 exams.