Croydon Council has been hit with a £100k fine after it failed to keep details of a child sex abuse victim secure.

The breach happened in April 2011 when an unlocked bag belonging to a social worker was stolen from a London pub.

Croydon Council said it was exploring the possibility of appealing the “wholly disproportionate” fine and added it was “perplexed and frustrated” by the investigation.

The worker was taking papers, including information about the sexual abuse of a child and six other people connected to a court hearing, home for use at a meeting the following day.

The bag and its contents have never been recovered.

An investigation by the Information Commissioner’s Office found that while Croydon Council did have data protection guidance available at the time of the theft, it was not “actively communicated to staff” and the council had failed to monitor whether it had been read and understood.

The council’s policy on data security was also inadequate and did not stipulate how sensitive information should be kept secure when taken outside of the office.

Stephen Eckersley, Head of Enforcement said: “We appreciate that people working in roles where they handle sensitive information will – like all of us - sometimes have their bags stolen.

However, this highly personal information needn’t have been compromised at all if Croydon Council had appropriate security measures in place.

“One of the most basic rules when disclosing highly sensitive information is to check and then double check that it is going to the right recipient.”

A spokesman for the council said: “Although we already have extensive procedures and protocols that should have prevented this situation arising, some of which appear not to have been taken into account by the Commissioner, we are now taking further steps.

“However, the council is perplexed and frustrated by the Commissioner’s general criticism of our Data Protection and information handling guidance, as many of our internal measures and policies appear to have been disregarded in reaching this judgement.

“The council also believes, having taken advice, that the level of fine is wholly disproportionate to the breach.

“We are therefore considering whether there are grounds for appealing against what we believe to be an excessive and unjustifiable amount."