And a Court Magistrate would accept an article printed on the confused.com website to be your defense? If the law isn’t broken, then there is no penalty. Anyone/everyone is welcome to put the relevant authorities ‘tolerance’ to the test though.
Minor speeding fines do not go to Magistrates courts. The vast majority (and probably all) police forces adopt a tolerance level of 10% plus 1 to 3 mph, whether you agree with it or not.