It’s been over a decade since I worked at an exam board, so my knowledge of results standardisation is not up to date, but the girls outperforming boys is not new. For a large part of the 20th century the girls’ results were adjusted down because they were outperforming the boys consistently and across the board, and it wasn’t considered socially acceptable to let those results stand. It was particularly marked in the early part of the century when only grammar and public schools were sitting exams.
For generations, boys were wrongly told they were academically more able as a birthright, and society believed that as a given. It’s no wonder they are struggling with the truth.
I do not trust these statistics, as someone who used to be part of the process for my subject. They are always subject to adjustment, which is inevitably decided by a notion of what the results ‘should’ be.