Sally and Peter both sat an A Level Humanities unit, but in different years.
There are four, equally weighted units needed to achieve the qualification. Both papers are marked out of 80 and both students score 61. But, as Sally's exam included more complex questions than Peter's, the grade boundary for achieving an A grade is set at 61. Peter's exam was relatively straightforward and the A boundary is set at 64.
Therefore, for this unit, Sally achieves an A and Peter achieves a B. Their marks are converted to UMS (out of a maximum of 80) as shown below.
Peter therefore has 61 raw marks with the A boundary for his unit set at 64. When this is converted into UMS, he has 60 uniform marks.
Sally also has 61 raw marks with the A boundary for her unit set at 61. When this is converted into UMS, she has 64 uniform marks.