Steps of St.Paul's

I was sketching people sitting on the steps of St.Paul's Cathedral, it was pretty crowded as it was unusually warm and sunny. This woman was sitting on my left and engrossed in a phone call. I drew her quickly then took this photo to blip later. I'm amazed she didn't notice me holding up the sketchbook and taking her picture. In my drawing she's aged by at least 20 years, but I still like it as a character study. I added a tint of grey to the shaded parts later.