Also the funniest. One of Lamb’s greatest joys is to take the piss out of the so-called slow horses, the ragtag crew of MI5 misfits under his charge. In the show’s first season, when one of them accidentally kills a fellow agent while tumbling down the stairs, Lamb cracks, “If you meant to kill him, he’d still be alive.” It’s a classic Jackson Lamb retort.
Yet behind the character’s contemptuous, world-weary exterior is a man who cares. “There’s a real loyalty to the slow…

