An ICO investigation found that Vote Leave sent 196,154 text messages promoting the aims of the Leave campaign with the majority containing a link to its website.

The investigation also found that Vote Leave was unable to provide evidence that the people who received the messages had given their consent; a key requirement of electronic marketing law.

Steve Eckersley, ICO director of investigations, said: “Spam texts are a real nuisance for millions of people and we will take action against organisations who disregard the law.

“Direct marketing is not just about selling products and services, it’s also about promoting an organisation’s aims and ideals. Political campaigns and parties, like any other organisations, have to comply with the law.”

Vote Leave claimed the information it had used to contact people was obtained from enquiries which had come through their website; from individuals who had responded via text to promotional leaflets; and from entrants to a football competition.

However, the organisation said that, following the conclusion of the referendum campaign, it had deleted evidence of the consent relied upon to send the messages. It also deleted details of the phone numbers the messages were sent from, the volume of messages sent, and the volume of messages received.

The ICO publishes detailed guidance on political campaigning and direct marketing explaining the legal obligations organisations have to comply with the Privacy and Electronic Communications Regulations 2003 (PECR).

This latest fine is part of the ICO’s ongoing investigation into the use of data in political campaigns. As a result of the investigation, the ICO has taken action against a number of different organisations engaged in campaigning for breaches of direct marketing and data protection laws.