Twitter does not show advertisements to famous and influential users with a large number of followers. The social network has started doing this to try and persuade high-profile users to keep using it; in turn, these celebrities will keep their hordes of fans engaged, too.

Sources at Twitter say the experiment to treat high-profile users better than the rest of us has been running since September 2015. Speaking to Recode, these sources say Twitter doesn't award the ad-free service (or a service with dramatically fewer ads than normal) to everyone with a high follower count, but by a variety of criteria, including the volume and reach of their tweets.

It is claimed the scheme is endorsed by chief executive Jack Dorsey, as the changes began when he became interim CEO in September, and are still in force now he has been made the permanent boss.

The strategy suggests Twitter is keen to keep hold of its most high-profile users, in the hope that their combined millions of fans will keep logging in (and seeing adverts, whose pay keeps Twitter afloat). Twitter generated over $2bn (£1.4bn) in revenue in 2015 and almost all of this came from adverts.

Instead of giving high-profile users a free pass on adverts, another revenue strategy could be to start charging all users a subscription, although this is not something which Twitter has considered publicly. The site said in a statement: "We're constantly looking at constraints and adjustments to optimise which ads are shown and how often."

Journalists at IBTimes UK, including those with verified accounts, still see promoted tweets. But Recode writer Peter Kafka, who broke the story, has 70,000 followers and does not see adverts any more.