The Instagram story trick Coleen Rooney used to accuse Rebekah Vardy – and what it shows about app’s privacy features

Coleen Rooney has claimed that Rebekah Vardy was watching her Instagram stories and secretly passing them on to newspapers.

It is an unusual story that has caused a very public fallout between the wives of two of England's most high profile footballers.

The claim sent shockwaves through British culture after it was made in a tweet by Rooney, and Vardy responded to suggest that it might in fact have been a consequence of somebody else using her Instagram account.

But it is also a reminder of the way Instagram works, and the very unusual options it gives to users – options that can protect a person's privacy, but also reveal unexpected things about users.

Instagram stories are a part of the app that allows users to post disappearing images or videos, which can then be viewed over the following 24 hours by anyone on the platform.

The trick that Rooney says she used to find out who had been passing on information from her private posts relies on a feature specific to Instagram stories, and not found on most other social platforms. When navigating through posts, you are not simply looking at the pictures and videos people shared – they're also looking at you, looking at their posts.

When someone posts an Instagram story, they can see a full list of the accounts that have viewed that story. Since it is not possible to look at stories unless a user is logged in, there is no way to see any post without being logged in.

What's more, those stories can be locked down, ensuring that only specific people can see them. If an account is private – as Rooney says hers was – then someone has to request to follow it; that means that only approved people can see stories or feed posts on a private account.

Once someone is following an account – whether it is private or public – people can also be blocked from seeing posts on a story. That means that people must be approved and also not blocked to see a post, which can be used to give very precise control over who is looking at Instagram stories.

Rooney says she used this feature to find out who had been taking information from her posts. She says that she uploaded stories but restricted them so that they could only be seen by one specific account – Vardy's, she claims – allowing her to know where any information had come from.

What's more, despite the fact that Instagram is unusually transparent about who has been interacting with stories, it importantly does not tell people who else has been viewing a story. That means there is no way to know if you are the only person who has seen a specific post, and therefore no way to know if only you know certain information.

In short, there are three particular features of Instagram that make such a claim possible. It allows you to shut down your account so that only approved people can see it; it lets you see who viewed your stories; and you can block specific people from doing so.

When combined, those three settings can be used as a powerful trick to allow people to see information without knowing that only they are seeing it.

It is rare that this will be used to work out who is passing on personal information to newspapers. But it could expose people in a variety of other, more pedestrian ways – and do so without the person using it even knowing.

Similar features do exist on other platforms. Snapchat, which had the stories features before Instagram, also allows people to see who has been looking at their stories, and even when someone screengrabs one; LinkedIn informs users when somebody has been looking at their profile.