The Concise Oxford Dictionary:
Confidential: 1. spoken or written in confidence; 2. entrusted with secrets
Secrets: 1. kept or meant to be kept private, unknown or hidden from all.
Misrepresent: present wrongly; give a false or misleading account or idea of.
The front of the Census form states: "Your personal information is protected by law. Census information is kept confidential for 100 years." Yet the law already allows it to be shared with all 27 EU member states, public bodies and approved researchers
By not stating that last fact, the Office for National Statistics has printed a blatant untruth and is therefore guilty of misrepresentation - something for which any commercial organisation would no doubt find themselves in court, it being an act defined in law as illegal.
Bear in mind that by asking us to complete the Census form, the ONS is offering us a contract - that our personal information is and will be kept confidential - but are prepared to break that contract with no warning that this will happen. On that basis I see no need for anyone to submit any information to anyone that is shown to be misleading us.