A/N: Not case-related, but a well-rounded doctor is always better to have on your side than one that had no life outside of his studies. I say this having known medical students from the year dot. I liked the idea of John as a singer, and as an expert mosher!

Greg smiled as John slid gratefully into the passenger seat of his car, hugging himself tightly as the cold of December seeped into his bones. "Cheers for the lift, Greg. It'd take hours to get across London in this weather-everyone's taking tubes or cabs."

"No problem, mate. Fancy some music?"

"Yeah! Yeah, why not. I've not done that in a while."

"When was the last time?" Greg asked, curious.

"Bombing down a dirt track in a Hummer in Helmand, blasting Hendrix out of the stereo. The base was so massive you needed a car to get around it, and it was just me and another three medics, air-guitaring and pogoing our heads off..." Shaking his head ruefully, John grinned as an appreciative smile lit up Greg's face as he bent to change the station. As neither of them were feeling like Hendrix at that precise moment, Greg skipped the rock channels, flipping past the crap pop of his godkids' generation as fast as he could. He settled on Radio 2.

"Radio 2, Greg? Like a bit of Terry in the mornings, do you?" John's smile was let of a smile than a wicked smirk, and Greg joyfully stuck two fingers up at him as he turned the wheel. Soon, whatever prog-rock monstrosity had been playing ended, and Sam Cooke's mellifluous voice drifted out of the speakers. Greg was fixed on navigating the madness of Piccadilly Circus when he heard something coming from his left. Stopping at the lights, he looked over. John was quietly singing along, hitting every note and sending a tingle down his spine. Feeling Greg's eyes upon him, his head snapped up, a fierce blush spreading across the apples of his cheeks.

"Nah, nah, don't be embarrassed! You've got a lovely voice."

John snorted, shaking his head and turning to look out of the passenger side window.

"John. I mean it. Where'd you learn to sing like that?"

"I never really learned as such-I never had lessons or anything like that, but I sang in a capella groups and musicals when I was at uni. I didn't sing that much after graduation. Wasn't much space for it in the army unless you were in one of the bands."

"You could always start again, y'know. Plenty of choirs and things around your neck of the woods. In fact," (at this point, Greg looked downright conspiratorial), "if you want a bit more of a gentle introduction, some friends of mine are putting together a carolling group at Covent Garden this year. It's for charity, so there's no pressure."

Looking doubtful, John wiggled his head from side to side. "You really think I could sing again?"

"Yep. Bloody hell, John, I can keep a beat but I can't sing to save myself."

At John's quizzical look, Greg smiled. "I was always the drummer."

Nodding, the younger man turned his eyes to the man in the driver's side. "Okay. I'll give it a shot."

Three days later, after the group's first rehearsal, he got a text from Marie-Anne asking him where he'd found 'the blonde one with the stunning voice'. Two minutes after that, he received one from John.

"Only gone and got a bloody solo."