1892. [Vastra says off-hand, setting the 'shirt' back on the rack and pulling out a skirt to examine.] London. The highest technology produced by humans that I can expect to see at home is a camera, and the closest any average woman comes to running a business is a hat shop. Not that I am average, however you've probably gleaned as much already.

[Skirt approved. Moving on...] What exactly is an 'arc reactor', if you don't mind my asking. [She smiles.]