That's it - they don't depend on the BBC. It's more a troubleshooting step. If the light in the kitchen doesn't work, but the one in the living room does, ther

That's it - they don't depend on the BBC. It's more a troubleshooting step. If the light in the kitchen doesn't work, but the one in the living room does, there's something wrong with the kitchen light. If everything's off, there's something wrong with your electricity. So if Northwood goes silent, but the cricket is uninterupted, there's probably something wrong with Northwood. If everything's gone, there's probably something wrong with your radio. But if Northwood's gone, the BBC's gone, but VOA is still up .. you start wondering if something's wrong with the UK. (For example. I'm not privy to anything the rest of us aren't. But it's clear that it's an item on a checklist that happens to have some novelty value, rather than being our "systema perimetr".)