The GMC's guidance Medical Students: professional values and fitness to practise (2009) is clear on this point. Paragraph 16(b) states that students should accurately represent their position or abilities. The student was advised to be aware of this when taking patient histories or providing any type of clinical care in future.
It is good practice for you to make every patient you see aware of the level of your experience and the extent of your capabilities.
The scene
A medical student was taking a patient history. While doing so, the patient addressed the student as 'Dr' and it became apparent that she assumed he was fully qualified. The student did not correct the patient but later contacted the MDU to ask for advice on how he should have handled the situation.
MDU advice
An examination performed by a medical student is not the same as one conducted by a qualified doctor. As a student, you need to make it clear to patients that you are seeking consent to examine them as part of your medical education, rather than for their direct benefit.