Bogus bobbies with detailed knowledge of police operations were preying on vulnerable pensioners and fleecing them of cash.

Their cruel trickery was so convincing that Islington Police chiefs carried out an investigation to make sure they weren’t genuine officers.

The phoneys, who carried fake warrant cards, picked on an 88-year-old woman in Highbury and a Holloway couple in their 70s.

Meanwhile, the owner of a Chinese restaurant was slashed in the face in his own kitchen.

Lam Ming, of Lok Hoi Chiu in Holloway Road, was chased by two boys and two girls – all about 18 – after they became abusive. He grabbed a knife for protection, but one of the boys snatched it and slashed him across the face. He needed stitches.