Since February, 43 reports of this kind of offence have been reported in the borough of Ealing. Fortunately there has been no financial loss in any of these incidents.

Courier fraud is a sophisticated fraud where scammers telephone the victim purporting to be someone from their bank, the police or other law enforcement agency. They then dupe the person into revealing their PIN and handing over their credit or debit card to a courier or taxi driver, who may not know they are being used as part of the scam.

The victim may be asked to ring the number on the back of their card, thereby further convincing the victim that the call is genuine, however the scammer keeps the line open so that the victim unknowingly talks to another member of the gang, posing as a bank employee.

Despite significant progress made in the past two years in tackling the offence, and advances in protecting people from this crime, police are warning Ealing residents to be on their guard as criminals work ever harder to defraud their victims as the crime continues to evolve.

Variations of the crime include:

- Asking the victim to assist in a police investigation. The victim is requested to withdraw a large sum of cash and take it home, where it is then collected by a courier.

- Being told there is a corrupt member of staff within the bank and asking for help in identifying them. The victim is told to withdraw a large sum of money which will be 'marked', with the purpose of it being placed back into the banking system. A taxi driver is sent round to collect the cash.

Police are advising the elderly and vulnerable to be aware of the following:

- Police and banks will never ask for your PIN or bank card;
- Never give your PIN or bank card to anyone;
- If you are contacted by someone who asks for these, hang up;
- Use a different line to report the call to police on 101 or allow at least five minutes for the line to automatically clear;
- Call 999 if the crime is in action.

Detective Constable Jim Egley, from the Met's Specialist and Economic Crime Command, said: "Much has been done in the past couple of years to tackle courier fraud, but scammers are always looking for new ways of defrauding the elderly and vulnerable, and the crime continues to evolve. It is vital that people stay vigilant."

"Courier fraudsters put a huge amount of time and effort into being convincing because the pay-off is immense. This is a massive part of what makes them so successful. We want people to question even truly genuine sounding calls and, most importantly, remember police and banks will never ask for your PIN or bank card, so you should never give these away. If someone on the phone asks for it, hang up immediately. If you believe you have had one of these calls or know someone who has, get in contact with your bank straight away."