It's fair to say that the government announcement that British passports will be blue once more after Brexit has received a mixed response. The Sun say it's a no less than stunning Brexit victory for the paper - which had been campaigning for the move - and Nigel Farage has also been quick to express delight. Others have questioned Theresa May's Brexit priorities. However, the issue that should worry the government isn't so much what shade they ought to be but the confusion over how much they cost.

There are reports online that the colour change will cost the taxpayer a cool £500 million. This is the claim doing the rounds today after James Caan, a former panellist on Dragon’s Den, suggested this on Twitter, linking to an old article by the Independent, from April, which referred to the Home Office launching a tender process for the design and production of passports from 2019. Although that article went on to state that this process would need to happen irrespective of any colour change, Caan appears not to have concerned himself with such details. He took to Twitter to claim the government had chosen to spend '£500m to change the colour of a passport while children sleep on the streets':

https://twitter.com/jamescaan/status/944129275321602049

Since then, over 30,000 people have liked the tweet and another 22,000 retweeted it. Meanwhile others have been making similar claims online - including Labour politicians like Angela Rayner, the shadow education secretary:

https://twitter.com/AngelaRayner/status/944138745988644864

It's true that from 2019, British passports will go back to the navy that was used for British passports until 1988. The confusion online over the price stems from the fact that when the current passport contract expires in September 2019, the new contract – which includes the colour change and will last 11 years – costs around £500 million. This is not to do with the passport being blue – it's down to redesign (for security) and manufacturing costs.

Brandon Lewis – the immigration minister – did say this in an interview on Good Morning Britain on Friday morning. But since then false claims have been made – and shared widely. This demonstrates the huge challenge the Conservatives face when it comes to controlling the narrative online. There's no silver bullet to the problem. It's clearly dishonest of Labour politicians to keep up tweets that they have been shown to be misleading and they should be called out for that. However, there will always be people trying to make the Conservatives look bad and social media means such claims can now spread like wildfire.

It follows that the Tories need to come up with a better way of handling it. Several Tory MPs – including Lewis – tweeted on Saturday from their personal accounts to try and correct the claims and get those people to delete their tweets. But this is a drop in the ocean. There has been little rebuttal from the Conservative machine – no mention on the CCHQ or official Conservative feed of the cost of the passports. For such rebuttal to have been truly effective it would have needed to have started earlier when it could have hopefully been nipped in the bud and by enough people (perhaps the Prime Minister?) that it couldn't be missed or ignored.

This isn't the first time the Tories have been caught off guard by a misleading story that has gone viral in recent months. The Conservatives spent weeks trying to undo the damage done to them by a story wrongly claiming they denied animal sentience. On both occasions the Conservatives did or said nothing wrong but regardless it led to a damaging incident.

Several senior Tories see the party's shortcomings in being able to respond effectively to the perils of social media as one of the biggest dangers it faces. It's been suggested that an independent neutral fact-checking organisation could be a solution. Independent or based within CCHQ, something needs to change if the Tories are to have any chance of escaping a fake news narrative – let alone setting it themselves.