Ahem. A pedant (for whom this has long been an intolerable personal bug bear) writes again. The principle on which the English judicial system relies, is, indeed, the "presumption of innocence" - either, as Malcolm points out, until the confirmation of the presumption via the due consideration of evidence, or its rejection in favour of a confirmation of guilt via the same process.
The problem that I have with the phrase "innocent until proved guilty" is that it is a logical fallacy. One is EITHER innocent, OR one is guilty. The two states are mutually exclusive. One cannot simultaneously be both, or be one, then subsequently be transformed somehow into the other. Even if one is presumed
to be innocent, that presumption is provisional, and one is guilty (and ONLY guilty) in actuality when that guilt is confirmed via the judicial process.