Duncan Paul, 51, of Glenorchard Road, Balmore, Glasgow, was the director of CRDNN Limited, which made millions of unsolicited sales calls in 2018.

Many of the calls were about window scrappage, debt management, window, conservatory and boiler sales while others falsely claimed to be working with Scottish and UK government energy saving schemes.

In one case, calls made to a Network Rail control centre near Fort William clogged up the line, creating potential safety problems.

The firm, based in Clydebank, Dunbartonshire, was fined the maximum £500,000 by the Information Commissioner’s Office in 2020 but went into liquidation without paying the fine.

Mr Paul’s co-director Stephen Foote, 44, was also banned as a director for eight years in January 2023.

Mike Smith, chief investigator at the Insolvency Service, said: “Duncan Paul’s company plagued homes and businesses with nuisance cold-calls, disrupting the lives of millions of people.

“The calls were persistent, totally unsolicited, and to add to people’s frustration, they received further calls when they attempted to opt-out of receiving them.

“Paul and Foote were the directors of this firm and we have taken robust action to prevent them each from running or managing any company for eight years.”

More than 63 million automated calls CRDNN made from June to the start of October 2018 connected. The Information Commissioner’s Office received almost 3,000 complaints from people during that period via its online reporting tool.

A further 411 complaints were received via the online reporting tool of the Telephone Preference Service.

CRDNN provided no evidence that recipients had given their consent to receive the calls.

Trevor Callaghan, the ICO’s Director of Enforcement and Investigations, said: “The directors of CRDNN knowingly operated their business with a complete disregard for not only the law but also public safety.

“They harassed millions of people, causing disruption, annoyance and distress and recklessly affected important services potentially putting the wider public in danger. That’s why their conduct called for the maximum fine possible under the law.

“The ICO is committed to building strong partnerships with other agencies, including the Insolvency Service, to ensure our work has long term, tangible impact.

“Disrupting the activities of these rogue companies and their directors ensures they can’t easily resurface under a different name and continue to cause further harm to people.”

CRDNN was fined £500,000 for contravening regulation 19 and 24 of the Privacy and Electronic Communications Regulations 2003 relating to the use of automated calling systems.

The company went into liquidation in January 2021 with the fine unpaid.

The Secretary of State for Business and Trade accepted a disqualification undertaking from Mr Paul, and his ban started on 2 May 2024. Mr Foote, of Meadow Rise, Newton Mearns, Glasgow, signed a disqualification undertaking which began in January 2023.

The undertakings prevent the two from being involved in the promotion, formation or management of a company, without the permission of the court.