A sprawling investigation into controversial digital marketing firm cambridge analytica and its associate company scl has found no evidence that it misused datain an attempt to influence the 2016 brexit referendum or help any russian intervention in political processes.

The three-year probe by the uk information commissioners office has been described by the authority as the largest ever undertaken by such an organisation.

The scl group, which was dissolved in 2018 and is linked to cambridge analytica in a complex corporate structure, had been accused by digital rights campaigners and whistleblowers of using illegally harvested personal data to influence the results of both the uk referendum and the 2016 us presidential election and breaking campaign rules.

Elizabeth denham, the information commissioner, told a parliamentary select committee on friday as part of her final report, that on examination, the methods that scl were using, were in the main, well recognised processes using commonly available technology. the findings were published on tuesday.

The ico had earlier turned over evidence to the national crime authority of a russian ip address, a digital identifier of where someone is accessing the internet from, it found in data connected to cambridge university from which scl drew its information. the ico said investigating the use of the ip address was outside its remit.

The ico, which has a mandate to enforce the data protection act in the uk, was asked to broaden its investigation into the use of personal data for political purposes in 2017 in conjunction with a request from the us academic david carroll.

Mr carroll, an associate professor of media design at parsons school for design in new york, made the request to better understand how his personal data was being used to profile him by cambridge analytica for microtargeting purposes in the us 2016 election campaign.

Alex tayler, formally the chief data officer at cambridge analytica, said: all the former staff of the company have had their reputations unfairly tarnished and these findings will be some comfort to them as they move on with their lives.

The ico noted it had successfully prosecuted scl elections for failure to comply with an enforcement notice to hand over data when they were already in administration, fining them 18,000.

It added it had identified various conduct issues within scl elections and its group of companies that it shared with the uks insolvency service. alexander nix, a director of scl elections, has since been disqualified from acting as a director for a period of seven years.

The insolvency service said the grounds for the ban were scl elections offering of the provision of unethical services including bribery and honeypot stings, voter disengagement campaigns, the obtaining of information to discredit opponents and the anonymous spreading of information.

The ico report noted its analysis included the processing of more than 700 terabytes of data seized from cambridge analyticas london offices under warrant in 2018.

The data revealed the companys well publicised claim that it had more than 5,000 data points per individual on 230m adult americans may have been an exaggeration.

On the findings, mr carroll tweeted the ico letterdistracts from regulatory crises to enforce laws on the books.