Two men have been held after raiders sneaked into a cash storage depot under a lorry and made off with £5million.
The masked gang wearing head torches strapped themselves to the vehicle before threatening staff and binding them with cable ties.
They then broke into vans full of cash destined for banks and ATMs.
Police would not say if the raiders were armed but no one was hurt during the March 29 raid on the Slough Trading Estate, Berks.
A 35-year-old from Slough was arrested last week on suspicion of plotting the robbery and concealing or transferring the stolen cash. Eight days earlier a 36-year-old from Birmingham was arrested on suspicion of robbery. Both have been bailed.
The fact that only one person was arrested on suspicion of conspiracy to rob means at least one further suspect is being hunted.
It is not known if police are aware of the identity of the other plotters or if they are believe to have fled abroad.
Belfast-based Pivotal Cash Management said after the robbery: “Our greatest concern is for our staff and while none suffered physical injury, we are working to support them.”
A recovery truck removed the lorry from behind the unit’s steel shutters. It was taken for forensic tests.
