It was a mistake that endangered thousands of people who had supported British forces in Afghanistan - and the Afghans' families.
For the first time, the Ministry of Defence has admitted it was responsible for a data breach that has been kept a secret for years - at huge expense to taxpayers - with the help of a super injunction that prevented media or parliamentary scrutiny.
Almost 7,000 Afghan nationals are being relocated to the UK following the blunder by the British military.
Mark Austin is joined by Sky’s security and defence editor Deborah Haynes, as well as one of the lawyers representing many of those affected by the leak.
Producer: Emma Rae Woodhouse
Editor: Mike Bovill