It is appropriately sneaky, thank goodness. He was a capable enough thief before having any magic up his sleeve but it's definitely better with it. Easier. In any case, Childermass doesn't reach for any particular spell just yet, focusing on the building again briefly.

"One last thing," he says after a few seconds, lips pursed and brow furrowed in thought for those, considering something. "The security cameras are those devices jutting out of the building. Is that right?"