The Information Commissioner, Elizabeth Denham, revealed that the ICO are working through the equivalent of 52 billion pages of information for their investigation into businessman Arron Banks.
At a hearing of the Commons Digital, Culture, Media and Sport Committee, head of the data watchdog, Ms Denham, revealed to MPs that the Information Commissioner's Office had gathered 700 terrabytes of data on Arron Banks’ insurance firm Eldon, and his Brexit campaign group, Leave.EU.
The revelation came after Labour MP Clive Efford quizzed Ms Denham on whether the ICO had enough information to carry out their investigation.
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Ms Denham said: "We have ceased servers, laptops, mobile phones and devices. We have, I think, 700 terrabytes of data which is equivalent to about 52 billion pages of information from Cambridge Analytica, information that's been provided to us by whistleblowers, by former employees of the firms, we have a lot of data that we've been working our way through forensically.
"We have to do it in a certain way because if we're pursuing criminal prosecution we have to retain the information in a certain way on a certain platform.
'It takes time'
She added: "It takes time. It's not that we need more information, it's that we need the time to finish the enquiry that we're doing."
The Information Commissioner's Office (ICO) said it had issued "notices of intent" to Leave.EU and Eldon Insurance for "serious breaches" of Privacy and Electronic Communications Regulations.
It followed the discovery of evidence that some Eldon customers' personal data had been used by Leave.EU to unlawfully distribute political marketing messages, the ICO said.