A Ministry of Justice spokesman said: "We treat the security of information very seriously and took immediate steps to recover the data as soon as the loss was reported to ensure that it went no further.
"These types of incidents are extremely rare but this does not mean that we are complacent.
"A thorough investigation was held by the prison who immediately altered their procedures, and further changes were implemented across the prison estate."
More top news
The former England cricketer reportedly suggested he would have a better chance of being knighted if he "blacked up".
Heavy thundery rain for parts of Northern Ireland and Scotland
Four men are being interrogated in Spain's National Court over the vehicle attacks that killed 15 people and wounded more than 120 others.