I'm a PhD student at a UK university. From what I've seen in my department (Engineering) there are about 3 women for every 5 men, both in staff and students, a not unreasonable ratio. However, I struggle to remember more than a couple of women who are British or from an English-speaking country. The majority come from India, China, the rest of Europe, the Middle East etc. I've also seen this in the six years I worked…
Do you not think this could be because immigrants are looking for economic prosperity and have fewer connections? For example, a British woman that graduates from a British university with a history degree and wants to work in the UK probably met a couple people during the course of her degree (or at any other point) that can help her move forward with a career. Because let's face it, you're not going to get a high-p…
I think a simpler explanation is that people choose a career in their countries for whatever reason (that I don't know and can't speculate about) then when demand for their skills rises, they may find that emigrating is a better choice than staying at home- for instance, because salaries are better abroad.
That would be a simpler explanation for why more women in IT professions are immigrants to the UK (and possibly the US, though I'm not sure): they got the skills, there's job offers, they go abroad and take the offers.