Prime Minister David Cameron’s plan for ISPs to filter porn from UK broadband services has been branded “ridiculous” by one of his Government’s most high-profile advisors, Wikipedia founder Jimmy Wales.

In an interview with Britain’s Channel 4 News, Wales was scathing about the idea of default porn settings for broadband accounts, describing them as “an absolutely ridiculous idea” that would almost certainly not work on a technical level.

As for stopping paedophiles, getting around the filter would simply require such individuals to opt in.

Announced last week during a speech at the NSPCC child protection organisation, the ‘great pornwall’ plan would require the UK’s largest Internet providers to ask new subscribers to opt in to receive pornography filtered using a set of criteria which has yet to be defined.

The plans have been attacked by a range of critics, including those who believe that the filter would be easy to circumvent, and by others who argue it would lead to a creeping censorship.    

Meanwhile, Wales was highly critical of the level of enforcement of existing laws against cybercriminal activity which he implied had taken second place to eye-catching attempts to create new laws and rules.

Billions of dollars had been spent on surveillance aimed to spot terrorists when more should be devoted to stopping the everyday criminality experienced by ordinary Internet users.

"We should devote a significant proportion of that dealing with the real criminal issues online, people stealing credit card numbers, hacking into websites,” he said. “But this is going to take an investment in real, solid police work."

Wales is an advisor on open access to online government but said he hoped David Cameron was listening to his views on other Internet topics.

In the light of revelations about surveillance by the US National Security Agency (NSA), Wales also said that Wikipedia planned to enable HTTPS encryption by default for editing access to its site, something he didn’t believe the intelligence organisation could easily beat using current technology.

“We are definitely in an era when we need to think a lot more about security in lots of different ways, one of which is the threat of government snooping on people and people hacking into websites,” he said.

Although Wales’s connection to the Government is relatively slight, his dismissive comments on the pornwall plans will be seen as an embarrassing rebuke for David Cameron, a Prime Minister keen to be seen as being close to the Internet’s influencers.