For a few seconds the Doctor just shot Jack a horrified look - the idea of prison never really appealed to him, but the idea of the Master trapped in a place like that... With the way he felt about him right now, he certainly couldn't let that happen.

Tools. Alright, good, something else to focus on before returning to that dilemma. "Tools, yeah. Search him, will you? Should still have the laser screwdriver at least." He lifted a hand to rub the back of his head. "And, er, if he gives you trouble you can hit him again, I suppose." That hadn't been easy to say.