Chelsea and Westminster Hospital NHS Foundation Trust has been fined for accidentally leaking the email addresses of 781 users of a HIV service.

The sexual health clinic 56 Dean Street, in Soho, which claims to be Britain's only service offering support for people who use dating apps , was fined £180,000 following a serious breach of the Data Protection Act.

It came after the clinic, which offered a service to patients with HIV to receive test results and make appointments by email, sent out a newsletter in September last year.

The error enabled anyone who received the newsletter to view the email addresses of the other recipients because addresses had been entered into the 'To' field and not the 'Bcc' field.

'Great deal of upset'

An Information Commissioner's Office (ICO) investigation found the trust had made a similar error in March 2010, when a member of staff sent a questionnaire to 17 patients in relation to their HIV treatment.

Again, instead of entering email addressed into the 'Bcc' field, the member of staff entered them into the 'To' field.

Information Commissioner Christopher Graham said: "It is clear that this breach caused a great deal of upset to the people affected.

"The clinic served a small area of London, and we know that people recognised other names on the list, and feared their own name would be recognised too.

"That our investigation found this wasn’t the first mistake of this type by the trust only adds to what was a serious breach of the law."

'We fully accept the ruling'

A total of 730 of the 781 email addresses contained people's full names, and a small number of people who received the newsletter did not have HIV.

The trust's medical director, Zoe Penn, said: "We fully accept the ruling of the ICO for what was a serious breach and we have worked to ensure that it can never happen again.

"I reiterate my apology to all those that were affected by this incident.

"The immediate safeguards we have put in place at Dean Street have included deleting the original email distribution list, limiting the opportunity of group email distribution, making the Option E Newsletter available only from the public website and, where group email is required, putting a two hour delay on recipients receiving group emails."