DairyCo has apologised for losing personal data of 13,000 farmers after an unencrypted laptop was stolen from one of its employees.
An employee from the company, which aims to solve "market failure" in the dairy industry, had the laptop stolen from their car last month. However, letters notifying the farmers involved were only sent out this week.
Philippa Stagg, head of communications at DairyCo, told the Yorkshire Post: "We obviously reported it straight away to the police and then we had to look ourselves into what was actually on the computer."
She added: "It took us 24 hours to ascertain that and what this information could actually mean. Because we took the investigation so seriously it took time."
Details of all the farmers who donated to the not-for-profit group were saved on the unprotected laptop, including names, addresses, quota details, transaction reference numbers and telephone numbers but DairyCo said no financial details were involved.
Chris McIntosh, chief executive (CEO) of encryption company Stonewood, called the incident the "icing on the cake" for an industry that has been struggling for the past decade.
"To be honest, it's good to see the affected farmers getting upset about this loss: hopefully, it shows people are becoming more aware of the threats lost data can present," he said.
"DairyCo is doing its best to reassure farmers, but they shouldn't feel they can breathe a sigh of relief just yet. The stolen laptop may not have contained deeply sensitive personal information, such as financial details, but even the smallest scraps can be of use to criminals who know what to do with them."
He added: "While DairyCo had implemented a programme of removing personal information from all company laptops, in this case it was evidently too little, too late."
A helpline for any farmers concerned has been set up on 02476 478887.
