Several robberies that have taken place between April and July this year are believed to have been linked, according to Thames Valley Police.

During the three-month period, those who were targeted were travelling to different locations to purchase high-value items with cash following conversations through Facebook Marketplace.

Investigating officer Detective Constable Yvette Wray, based at Milton Keynes police station, said: “This is a concerning series of robberies and enquiries are ongoing in relation to these investigations.

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“I do not want to discourage people from using online marketplaces, such as Facebook or Gumtree, as the majority of buyers and sellers are genuine.

"However, there are some steps you can take to protect yourself when making a transaction.

“Do not give out personal information, such as your home address, when exchanging the item and any cash payment.

"Meet the seller in a public place that you both agree to and take someone with you.

"If something does not feel right then do not go ahead with the purchase, you are always free to walk away.

“Facebook Marketplace also offer their own advice on buying and selling which can be found on their website.

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“We are appealing for any witnesses to these incidents, or anyone with any information that can help with this investigation, to get in touch with us.

"You can do this online or by calling 101 quoting reference number 43220303180.

“Alternatively, you can contact the independent charity Crimestoppers anonymously via their website or on 0800 555 111.”