I thought Bletchley was a bit under-represented on the old cache front so I've slipped in a couple. They're fairly straightforward but the fun is going to come from all the muggles you will encounter. The difficulty rating reflects this. Please be circumspect and utilise all your "deflection of attention" skills to preserve the longevity of these caches.
Sit facing Queensway and reach under.
This cache is called "Sweet", can you work out why I called it this? If you email me your answer I'll give you a clue to "Stargate Universe"