Gosh, it is honestly bizarre to find this here. I posted this several years ago (I believe) on r/finance, after a number of years of being pestered by various hopeful future bankers and a lot of misinformation on that subreddit itself. I've since deleted my account, but upon trying to find the thread via google, stumbled upon this seemingly well-preserved repost. I'm glad, though a little surprised, you've taken some of it to heart.
To reply to some recent (though several month old) posts, in case anyone in future stumbles across them, especially the ones regarding those rather ominous university figures (with 85%+ from Oxbridge/LSE etc..) I have to say that hasn't been my experience *at all* - in fact I'd be very interested to know where that data comes from. It's true more graduates are from targets, but remember - Oxford and Cambridge have many more students *interested* in finance, or with relevant connections, than the other places- the fact that the number of students at Manchester or wherever is much lower is as much about the fact that far fewer from Manchester apply than the fact that those who do don't make it!