I think there are two parts to this.
Do we want more girls to become engineers?
Yes.
Do we want more of the girls who currently study Physics at A level to become engineers?
I would say no. About 30% of the girls doing Physics go on to medicine, dentistry or to be a vet. About 10% of the boys do. I do not want engineering poaching women away from medicine. We really need female doctors.
Physics is really hard at A level. A student who got B's at GCSE will probably get a C in most subjects at A level, but will probably get a D in Physics, according to the stats from A level results. This is not some Science is harder thing; A level French is also really hard compared to other subjects.
Unless somebody really loves Physics, or wants to do it for its hardness so they stand out when applying for a competitive course ( like medicine) or they want to be an engineer or a physicist or similar, it is foolish to do A level Physics. It might reduce your grades for university.
Of the girls doing Physics, 36% of them get an A compared to 28% of the boys. So there is no question of the girls' capability at the top level. They are not choosing other university courses because they are not good enough at Physics. They are good enough.
If Physics, Maths and Engineering want more women, they should be poaching more girls at GCSE phase who are currently opting out of Science completely at A level, not poaching those girls doing Science A levels who are heading towards the life sciences.