Mr Shea stopped in his tracks at the titters. "Yes, that's right," he said, "the sound of angels." Reading everyone's mind, Mr Shea added: "I could never have put it so eloquently."
This was false modesty. Mr Shea's daily briefings are a catalogue of soundbites and powerful quotes. The Serbian leader is Pol Pot or Al Capone. Fleeing refugees stripped of their identity documents are going through "an Orwellian nightmare" or "trading in their property rights for a train ticket to oblivion".
Live television broadcasts of his news conferences have turned Mr Shea, 45, into a household name. In fact he is a reluctant star and his new role as Nato's frontman, constantly in the spotlight, churning out selective information and overblown rhetoric, is something those close to him believe he is uneasy with.
He is a favourite with the press. It is hard to find a journalist with a complaint.
Affable and unassuming, his courtesy and air of local-boy-made-good contrasts with the style of other British spin doctors, such as Alastair Campbell, or Gordon Brown's former mouthpiece, Charlie Whelan.
Someone who first met Mr Shea when he was a Nato minute-taker stresses how he has remained a modest man: "He is not a performer. He is uncomfortable when he has to accompany [the Nato secretary-general] Solana to London and they stay at Claridge's. He'd rather go to the pub."
Mr Shea is now being blamed for a number of Nato "exaggerations". Two French newspapers this week accused him of "propagating rumours". Now he has been embarrassed by Nato's admission it bombed residential districts in Pristina.
Those who know him say he is sincere in his feelings. As the messenger for Nato's actions and policies he is now being shot for Nato's mistakes.
But Mr Shea is more than a messenger. He has allowed himself, however reluctantly, to become the public face of the allied campaign. And, having started, he must go on justifying it, whatever happens.Reuse content