I sometimes think the world was a better place before the internet. But then all of a sudden I need to check which member of Bananarama married Andrew Ridgeley and I remember that I couldn’t live without Google.

Amber Rudd has a lot more on her plate than 80s pop trivia. Yet her response to questions about the apparent use of WhatsApp by Khalid Masood in the moments before last week’s terror attack suggests a level of technological understanding that is about 30 years out of date. For while few would argue that tech firms shouldn’t do more to tackle the promulgation of extremist material, to say blithely that the police should be able to access encrypted messages is breathtakingly naïve.

For one thing, it is end-to-end encryption which – for many people – makes messaging apps attractive. The increasing ability of criminals and foreign state actors to hack into private information online has made the public vastly more aware of the potential threat to their data. With online messaging services now much more popular than traditional SMS (42 billion messages sent per day, as against 20 billion texts) the security of WhatsApp, iMessage and others is – for most users – a pro, not a con.

Ex-cyber security chief says Government 'using' Westminster attack

The Home Secretary argues that messages need only be accessed in circumstances where the police or other authorised agency has been granted a warrant through the proper channels. But of course opening up any potential backdoor access creates a vulnerability which hackers will be desperate to exploit. This is not about imperilling the revenues of Facebook-owned firms like WhatsApp, but about exposing the personal data of millions of people to an increased risk of interception by criminals. That is why the argument that “those who have nothing to hide have nothing to fear” is much too simplistic.

We should remember too that there is, as far as we know, no firm evidence that Masood used WhatsApp for nefarious purposes – either in the minutes before he brought murder and mayhem to London’s streets, or at any other time. True, it is that which has brought the question of encryption into such sharp focus, for if he was communicating with accomplices it is eminently explicable for the police to want to know about it. But for the Home Secretary and Prime Minister to use an explicit absence of evidence as the basis for their criticism of messaging apps is bold to say the least. When the changes they seek could arguably do more to undermine personal, and even national, security than to protect it, such boldness looks misplaced.

What’s more, the internet is a place where a thousand flowers bloom. If WhatsApp gave end-to-end encryption the heave-ho, another service would pop up in a matter of days. If the Government really wants to control the way web firms operate and the way Britons access the internet, it will need to take a leaf out of China’s book.

In pictures: Westminster attack Show all 9 1 /9 In pictures: Westminster attack In pictures: Westminster attack An air ambulance lands after gunfire sounds were heard close to the Palace of Westminster in London PA wire In pictures: Westminster attack MPs wait until the situation is under control in Westminster. 'The alleged assailant was shot by armed police,' David Lidington, leader of the House of Commons, told the house. BBC News In pictures: Westminster attack Crowds gather in Westminster after shooting incident, which police are treating as terror attack BBC News In pictures: Westminster attack Police were also called to an incident on Westminster Bridge nearby AP In pictures: Westminster attack Early reports indicate the car, which mounted the pavement on Westminster Bridge and mowed into around a dozen people, was the same vehicle which then rammed into the railings of the Palace of Westminster, just around the corner Reuters In pictures: Westminster attack Security sources described the suspected assailant as a middle-aged Asian man, who is understood to have left the car before attacking a police officer with a seven-to-eight inch knife PA wire In pictures: Westminster attack Police have asked people to avoid the immediate area to allow emergency services to deal with the ongoing incident AP In pictures: Westminster attack One woman has died and a number of others, including the police officer, have been hurt, according to a junior doctor at St Thomas' Hospital Reuters In pictures: Westminster attack At least three gun shots were heard by those inside Westminster, and proceedings in the House of Commons have been suspended AP

Rudd’s plea appears to have struck a chord with some sections of the traditional media, in part no doubt because the desire to explore ways in which the terror threat to Britain can be reduced is thoroughly reasonable. But it is notable that big tech firms such as Google and Facebook are already the subject of a deeply critical media narrative: slammed for failings over the placement of legitimate adverts alongside inflammatory content; condemned for doing too little to combat extremist websites and for enabling the dissemination of fake news; slated for maintaining the line that they are merely ‘platforms’ and thus cannot be held responsible for content created by others. The Home Secretary’s attack on WhatsApp fits neatly into this analysis

And sure enough, there is something in it. Full-on libertarian attitudes are all very well in a sunny California startup, but they don’t stand up to much scrutiny when spouted by vast, and hugely profitable, multinationals. Google and Facebook can’t carry on with the *innocent face* routine forever; and they know it.

But there is a murkier battle here too, between established media brands which are anxious about declining direct ad revenues, and the online giants which are soaking them up – and doing so in part because they provide the window through which people increasingly consume their news. Attacks against Google et al by tabloid newspapers have to be seen against this complex backdrop.

In the end, the world’s major tech companies cannot be ostriches. They will have to do more to combat the spread of hate online. They must accept that being a ‘platform provider’ is not a get-out-of-jail-free card when it comes to avoiding responsibility for hosting highly inappropriate material. They may also have to reconfigure their relationships, commercial and otherwise, with major media brands to one of symbiosis, not conflict.