Which might have been presumptuous of Sherlock, but he never concerned himself with social niceties. They only got in the way. And he was about eighty-five percent sure he was right.
"That book doesn't even apply to The City. There is no Egypt here to speak of. You're looking at a text from another world where you never existed. I wouldn't be alarmed."
Which was more or less his way of saying he didn't care. Sherlock hadn't approached her carefully or politely. He was just there. Out of hiding from exploring or researching whatever he was up to behind The City's back. Other people might have been upset with him for that but there was only two, possibly three criminals in this town that were mildly interesting and it was highly unlikely due to the City's nature that they were going anywhere. Plenty of time to deal with them later.
"You should learn to use a mobile if you haven't already. Also a computer. A lot has changed since your day."
Whether she wore modern clothing was irrelevant. Sherlock observed, much like she did.