The incident happened at around 1.30pm on Tuesday 2 April 2024.
A woman in her 70s reported a gold chain she was wearing was forcibly taken after she was approached by a woman outside a property near London Road.
It is alleged the victim had spoken to the woman earlier the same day outside a supermarket in Orpington, while the latter had been seeking signatures for a charity.
A 30-year-old woman from Edmonton, Greater London, was arrested by officers shortly after the incident on suspicion of robbery and taken into custody.