I agreed to a medical student observing, then felt uncomfortable. Can I change my answer?

At my NHS appointment in England, the clinician asked whether a medical student could stay. I said yes while the student was already standing by the chair.

The appointment involved discussing an intimate symptom. Once the questions started, I gave shorter answers than I had planned. Nobody mocked me or did anything obviously wrong; I just wanted one fewer person listening.

I asked the clinician to pause but could not bring myself to say why. I have another appointment with the same team and would like to ask for no student observer this time.

[GMC guidance says patients should be able to object to student involvement without prejudice to their care, and that consent should be sought for a student observing](https://www.gmc-uk.org/education/standards-guidance-and-curricula/guidance/undergraduate-clinical-placements/guidance-on-undergraduate-clinical-placements/patient-safety).

I support students learning. I also want to give a complete account of the symptom. How do I make that request without turning it into an apology to the student or a complaint about the whole visit?