A conman tried to trick a Norfolk woman out of cash by posing as a detective from Scotland Yard.
Officers are reminding Norfolk residents to be vigilant following another incident involving a cold caller claiming to be a police officer.
Theresa May has warned that Britain is in the grip of a spate of copycat terror attacks in the wake of the London Bridge atrocity.
Police have confirmed the London Bridge and Borough Market incidents were terror attacks, the third to hit the UK in less than three months following the Westminster and Manchester atrocities in March and May.
Witnesses have described seeing a speeding vehicle veer into crowds on London Bridge and people being stabbed in Borough Market, as police respond to incidents in the capital.
Seven people have been arrested in raids in London, Birmingham and elsewhere linked to the Westminster terror attack, police have revealed.
The police officer who died was named by Scotland Yard as Keith Palmer, a 48-year-old husband and father.