A prototype security device promises to film pilferers in the act and email you the evidence. But is it worth entering a moral minefield for the sake of 15ml of semi-skimmed?

When you head to your workplace fridge, only to find that some thoughtless colleague has nabbed your milk, what is the appropriate response?

a) Shrug it off and say: “Oh well, that only cost me around 8p when you think about it”;

b) Steal someone else’s milk, thus reinforcing this endless cycle of resentment;

c) Resolve to find out the culprit and then plot their downfall over the coming weeks, months or even years using whatever underhand methods you deem necessary.

If you answered a), congratulations on not being a psychopath. If you answered c), don’t worry – you’re not alone in your ludicrously OTT response. According to research by security provider ADT, having minor items taken can have a dramatic effect on people’s lives. Four per cent of 2,000 people surveyed said that they had broken up with someone over such petty pilfering, while 3% claimed to have moved house just so that they didn’t have to endure the pain of seeing their Hobnobs stolen.

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Inspired by this, the company has created a new alarm, designed not for protecting houses or cars, but any small item you don’t want to go missing. Whenever a thief comes within 50cm of the device, it takes a high-definition picture and sends it the owner an email warning them that their property is at risk.

Even before I tested the device, it threw up awkward philosophical questions about this brave new world. Such as: do I want to catch the milk thief? I hate confrontation more than I hate losing 17ml of full-fat milk, and if a picture of the nice woman from the subeditors’ desk arrived in my inbox, I wouldn’t want to go up and shout at her.

Then there’s the sheer weirdness of it all. I felt a pang of guilt while waiting for my inbox to provide me with a blurry photo of a colleague’s earlobe: the secret camera might have innocent intentions, but it felt pretty intrusive. Say I plucked up the nerve to confront the nice woman from the subs’ desk and she denied it – would I really bring out the hidden-camera shots of her committing the crime? If so, would she be in the wrong, morally? Or would I, the filthy fridge pervert, be the one who ended up doing time when it reached court?

Thankfully, it never came to this. The prototype alarm relies on a mobile signal to send images, and that cut out as soon as the fridge door was closed. It was too big and cumbersome to attach to most items (who would try to steal a bar of chocolate that had a massive ADT alarm attached to it?), and would only really work in a very specific setup – say, catching your kids entering a forbidden cookie cupboard.

For now, such alarms belong more to a vision of the future – one where anyone can film anyone doing anything, anywhere and have the evidence emailed to them. Sounds terrifying? At least you’ll never be unable to make tea.