There is a stretch of tunnel at London Bridge station, linking the Underground with the Southern Railway platforms, which is lined with half-a dozen shops of the sort that you make an emergency visit to when you are on your way to someone’s birthday party and you have forgotten to pick up a card. It is dingy and badly-lit, and the clock overhead is wrong for at least six months of the year. It is not a place you would choose to linger for longer than it takes to buy a birthday card.

In the last few months, though, it has become even more offputting. Now, as you walk through, you have to dodge large puddles of water, in the middle of which sit optimistically-placed buckets and the odd “Caution Wet Floor” sign. Sometimes, you have to dart at odd angles across the corridor to avoid being dripped on.

Now.  We’ve had a lot of rain this summer, I know that. But it rains a lot in winter and autumn, and it has never caused the roof of the station to develop this many leaks. Call me crazy, but I can’t help wondering whether the 310-metre-high building which has been built inches away from the tunnel could be at least partly responsible for this sudden instability.

If you are an engineer and can tell me why I’m completely wrong, please do, ideally before this evening when I will have to make the journey again. A crowded, sweaty, stinky commute is one thing. One carrying even a minimal danger of becoming crushed in a collapsed heap of brickwork and birthday cards is quite another.