Explosives were discovered attached to the underneath of a lorry in Sussex on Thursday.
Two plastic cases containing guns, grenades and ammunition were found underneath the HGV, held on by magnets, at Rosier Business Park in Sussex.
Armed police and military bomb disposal teams swooped on the area in dramatic scenes.
The area was surrounded by officers and a 100metre exclusion zone was set up as buildings were hurriedly evacuated.
Police said armed officers along with officers from the National Crime Agency cordoned off part of Rosier Business Park in Billingshurst this afternoon
The National Crime Agency (NCA) confirmed they were investigating the driver for importing explosives.
The driver, a man in his 40s, was arrested at the scene.
The huge bust comes as police have been put on high alert around Windsor, for the wedding of Prince Harry to Meghan Markle.
Anti-terror barriers have been erected around the town centre and on the route leading to the castle.
Britain is currently on high alert with the security services warning the threat level for international terrorism is ‘severe’. According to MI5, this means an attack is ‘highly likely’.
NCA Branch Commander David