@Actualizer my d is an American at Cam, but there are differences as she applied from France and is also Irish (i.e. she did not take APs. but did a French bac). I would strongly recommend that you read through this thread - it demonstrates how individually attuned the process is, but also gets into a lot of relevant issues.
http://www.■■■■■■■■■■■■■■.co.uk/showthread.php?t=3120743
Inserted below is my description of the process for her.
Most important, you must know what you want to study, i.e. your major - the 3-year course combines curriculum from undergraduate and graduate levels. That means you should demonstrate, through focused experience and effort, that you have been pursuing your interests. Some disciplines are easier to get into than others, e.g. Classics v. medicine. After that, there are many hurdles and requirements.
First, to apply, you have to meet strict grade requirements. If you are a foreign applicant, from a different system, this adds a bit of flexibility, but not much.
Second, if they are interested in you, they may ask for additional personal essays that require research and an expression of the applicant’s own thoughts. Parents are instructed to let it be a pure product of the applicant, with no writing help. I was very impressed with this, as it was a growth experience for my daughter.
Third, they can invite you for an interview on campus. Beyond probing what you know until they stump you, this is to check if you have the “right attitude”, that you “shine” yet know your limits. It was an exercise in humility for my D.
Fourth, they can ask you to take tests in your topic, though this was not required of my daughter.
Fifth, if they make you an offer, it is conditional. They set precise overall grade requirements (or class ranking) - my daughter had to get very high grades on her BAC exams (in her French high school), in some cases for specific disciplines; my daughter had to get A+ in honors math.
For this final hurdle, we formulated a strategy. We looked at her strengths and got a tutor to prepare for her BAC exams (they demand a specific style of answer, which was what we prepared for - not content, but style), in a sense knowing what she could ace and how it was weighted to affect the overall score. We avoided emphasis on subjectively graded subjects, such as philosophy, and concentrated on those over which we had more “control”.
Directly comparing statistics between US and UK admissions processes is misleading. First, with the common UK application, you can only apply to 5 schools. Second, you cannot apply to both Cambridge and Oxford. Third, the grade requirements are rigid, eliminating many qualified applicants from the statistical pool. Fourth, there is no “legacy” advantage, though if you go to the right public (read “private”) school in Britain, you are conditioned for the culture. Finally, my D applied as a European, though she could have done as an American. Americans may have additional requirements, such as submission of SATs.
I should note that applicants have to choose a college within Oxbridge to apply to directly. If that one lacks places in the chosen discipline but thinks the applicant is qualified, they are put into a “pool” with other colleges, which can choose to repeat certain steps in the application process. My D was “pooled” from St. Catherine and offered a place elsewhere. Also, extra-curricular activities are not very important; that being said, my D is an accomplished singer, which we believe helped as she was asked to audition in person for the chorus while still on conditional acceptance.
As one can imagine, it was a long and stressful process right up to July, when her BAC results were posted at school. We were focused on the process for the last 2 years, though from age 12, my D had expressed interest in going to Oxford and had read a book about how to get into Oxbridge. (As it turned out, she visited Oxford at 17 and didn’t like as much as Cambridge.) While my D was motivated to pursue her field on her own, we also nurtured her interests and offered her opportunities for work experiences in it, which she loved.