When a fraudster from Wembley decided to carry out a laptop scam on an unsuspecting buyer in Edgware he picked the wrong man.

Brian McDonagh, of Hillfield Avenue, thought his was luck was in when a man agreed to buy a laptop, tablet and a mobile phone from him after he offered the goods for sale.

But unbeknown to the 34-year-old his ‘victim’ was an off-duty policeman who recognised the Modus operandi of the scam and played along with him to gather evidence.

The scam occurs when a fraudster offers a genuine laptop for sale.

The computer is shown to the victim but is swapped with an identical bag containing bottles of water which is handed over once money is exchanged.

When McDonagh was arrested, officers found a laptop and Ipad inside a laptop bag and an identical laptop bag of similar weight containing water bottles in his car.

He claimed he was innocent but officers were able to link the laptop he was trying to sell to previous offences.

Last week at North West London Magistrates Court he was found guilty of possessing of articles for use in fraud.

He was given a four month prison sentence suspended for two years and was placed on a curfew with electronic tagging.

He was also ordered to pay £85 in costs and a victim surcharge of £80.

PS Jamie Kay said: “I would urge people to be cautious when buying property on the street at a price that seems too good to be true and I would encourage suspicious activity to be reported to the police.”