Service in Westminster Hall on terror attack anniversary

The video begins with a gathering where the speaker thanks attendees and acknowledges those who prepared for the event. It then moves to discuss active commitments, encouraging participation. The main focus is on remembering and honoring individuals who showed courage and self-sacrifice, particularly PC Keys, who made the ultimate sacrifice for safety.

How does the text describe the actions of PC keys in the face of danger?

What ultimate sacrifice is referred to in the text?