Thorburn lit the candle in the tunnel with the one taken for his investigation before extinguishing it and returning it to it's resting spot. He looked around for a moment to ensure they weren't leaving evidence of their visit behind, then he waved Stuart through and closed the door behind them making sure it latched. Down the tunnel, up the stairs at the end, blow out the candle before moving the cabinet, out and close behind them. Return the candle to the drawer, get a boost from Stuart, reach down and pull him up and they were both sitting on the roof again, with plenty of darkness to get away....