The 32-year-old, who has just returned from a break in Thailand, attended the gathering of the Westminster Safer Neighbourhoods group near her home in St John's Wood.
She chatted to police officers who asked her if she had any concerns about crime in the area.
On leaving the meeting, Kate was pictured without a wedding or engagement ring, fuelling more speculation about whether or not she tied the knot with on-off lover Pete Doherty in Phuket.
