Around £80,000 worth of suspected stolen power tools have been seized by police at a car boot sale in west London.
The Metropolitan Police recovered 400 items in the operation on 11 December.
Two men, aged 55 and 54, and two 15-year-old boys have been arrested on suspicion of handling stolen goods.
The objects seized by officers at the Hounslow Heath car boot sale included power drills, nail guns, electric saws, and a concrete mixer.
It comes after shadow justice secretary Robert Jenrick visited the sale last month and posted a social media video highlighting concerns about the sale of suspected stolen goods.
The Met said its operation was in response to worries about tool theft and was working to identify the tools and trace their original owners.
Superintendent James Rawlinson, of Hounslow's local neighbourhood policing team, said: "We are listening to Londoner's concerns about tool theft because we understand the significant impact it has on tradespeople and their livelihoods.
"We are targeting the prolific offenders and organised criminal groups that drive this trade in stolen tools through proactive, intelligence-led operations."
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The force said tool theft between April and December was down 20.3%, compared with the same period last year as a result of Met operations targeting tool thieves.
Officers seized more than £500,000 worth of stolen tools during operations at two large-scale boot sales and associated premises in Romford and Rainham and made several arrests earlier this year.
Police have advised power tool owners to mark and take photographs of their property, and record the items' serial numbers, to increase the chance of returning them if stolen.
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