Parenting advice company Emma's Diary has vowed to never again share personal data with a political party after it was fined £140,000 by the Information Commissioner's Office (ICO).

Britain's privacy watchdog announced that Lifecycle Marketing, the company behind Emma's Diary, had collected data belonging to more than one million people.

The information was sold to Experian Marketing Services, a branch of the credit reference agency, specifically for use by the Labour Party to profile the new mums in the run up to the 2017 General Election.

The Labour Party was then able to send targeted direct mail to mums living in areas with marginal seats about its intention to protect Sure Start Children's centres.

A Lifecycle Marketing spokesperson said the company has been supporting parents for over 25 years and that it works in an "ethical and professional manner".

"The ICO matter is related to data we provided to Experian, some of which was used by the Labour Party for a one-off mailing in connection with Sure Start Children's centres," the spokesperson said.

"We had never previously provided data to a political party and we will never do so again.

"We have always sought to fully comply with our data protection obligations, which we take extremely seriously, we are sorry that on this isolated occasion our interpretation of the DPA has not been in line with the ICO's."

"We are fully compliant with the new GDPR and give our parents complete control over the communications they receive."

After announcing the fine, Information Commissioner Elizabeth Denham said: "The relationship between data brokers, political parties and campaigns is complex. Even though this company was not directly involved in political campaigning, the democratic process must be transparent."

This case formed part of the ICO's investigation into data analytics for political purposes.