Actually a difficult sort of clue, because this area is above the mystery, padlocked doors and not behind them….
But if you know where this is, you can probably work out the rest.
I actually took the photo originally because I was intrigued by the ‘line of liner funnels’ at the far end. I think they must be something to do with ventilation or heating but didn’t have a chance to look closer. In fact it was rather strange wandering round as the space was completely deserted – not even the usual Camberley pigeon.