The slate quarry near Skarloey was taken over by the Ministry of Defence for the storage of ammunition after its closure. The MoD used their own engines to shunt the sidings in the quarry, black electric-powered engines described as "beetle-like". Due to the highly secretive nature of their work, the engines have rarely been seen. Only some lucky engines have seen them. Some say they work for the government, but since they are hardly ever seen, no one will know for sure.
They look to be small Hunslet diesels, similar to Fred.
- The Lorries (cameo)
The Ministry of Defence Engines have no allocated voice artists as of now.