the driver , one of mi5 's finest , excused himself with a salute and a barely suppressed grin , and took himself off , officially to give the bridegroom time alone with his friend if he wanted it , unofficially because the mi5 drivers , as a group , had , now that his limo phobia was out in the open , adopted triple-o five as a special case in need of particularly compassionate care , much as if he were a beloved nephew with rare and misunderstood handicaps .