According to images taken by the security surveillance cameras at luxury jeweler Graff Diamond Jewelry, a previous attempt to carry out the biggest jewel heist in Britain's history was made before it was pulled off about a week ago.

The Guardian reports that the photographs displayed two men standing outside Graff Diamond Jewelry on the Tuesday before the luxury jewelry robbery. According to Detective Chief Inspector Pam Mace, the police believe that the two were planning on committing the robbery on August 4, but decided to abort the operation.

A £1 million reward has been offered for information that will lead to the capture of the luxury jewelry robbers, as well as the whereabouts of the 43 diamond necklaces, bracelets and earrings they stole.

The new photographs show the two perpetrators wearing clothes similar to the suits worn during the actual jewelry robbery. Both suspects are in their 30ths, and speak with London accents.