She's an MI6 doctor who gives Bond a "clean bill of health" and descibes the effects of 009's bullet traveling through Renard's brain.
How she and Bond meet:
Bond has been placed on the inactive roster by M for a broken collar bone suffered as he fell from a hot air balloon while chasing Cigar Girl. Bond visits Warmflash's office, seduces her, and gets his clean bill of health.
How she helps save the day:
She clears Bond for active duty and describes Renard's high pain threshold to Bond.