Mine detectors
After the fiasco of the "mine detectors" that didn't and which were bought by the MOD, I can't help feeling that the requirement of secrecy just opens the whole thing to more fraud in which someone leaves the MOD with a golden parachute and the delivered product is a black box with a car aerial on top and a red and green light labelled "Terrorists" and "Safe", powered by a pp3 battery and containing a mystery lump encapsulated in epoxy.
The organisation that couldn't even supply the Army with proper socks has quite a track record to overcome.