The Princess Royal visited the Probation Service in Borough High Street on Tuesday.
Passengers leaving Borough Station were surprised to see the Princess on the pedestrian crossing.
After 90 minutes the Princess, who was visiting in her capacity as patron of the Butler Trust, left for a lunch engagement in St James's.
For the latest local news and events direct to your inbox every Monday, you need our weekly email newsletter SE1 Direct.
7,000+ locals read it every week. Can you afford to miss out?
Read the latest issue before signing up