The interviewer wants to see if you've taken the time to research the NHS and learn more about why they do what they do, their mission, and their core values. Demonstrate that you're being intentional about applying to organisations you're interested in and not just any job that's posted. Take the time to speak about what you've read about the NHS, its leadership team, its mission, what they value, and the patients they serve. Perhaps you know someone who works there, or maybe you've been a patient of theirs in the past. If so, share that experience! Also, being able to speak to any specific awards or achievements the NHS has earned is an added bonus!