<p>Most European universities allow students to double-major, but a double major entails twice the course load of a single major. You would actually have to fulfill the requirements for two full degrees since degree programs in England contain no single elective outside of your area of concentration. I haven’t heard anything about Cambridge in particular, but a double major would seem rather contrary to the mission of the school. Cambridge wants its students to invest themselves into their major to the best of their abilities. This value might be best reflected in the format of instruction, which you are most definitely aware of.</p>
<p>The programs that KING IS HERE mentioned are set up to be interdisciplinary (the most famous examples are PPE and the Natural Science Tripos). But it is usually not possible to construct an interdisciplinary major the way one might design an independent major at an American university.</p>