There was a time when London became a ghost town. Perhaps it was a time or two depending on how you look at the figures.
Once was when the Romans looking at the diminishing grain crops from overworked field systems, costs incurred by deforestation, worked out mineral seams, monetary problems and the need to import slaves to get the work done, decided enough was enough and left.
Another was because of Yersinia Pestis, no, not a war lord, but the bug that caused The Black Death in the 14th Century. There was a major setback in the late 17th Century with The Great Plague. Perhaps we are due for another.
If this does happen soon it may well be a man made one. But with contributory factors involved that might make matters worse. If the ancient gods have their way with their sense of humour it ought to happen when the planned HS2 rail line opens for business.
We may think it cannot happen in the modern world. But we only have to see what has happened in the USA where many towns have been shattered by the financial crisis and districts and towns deserted.
In China there are whole cities almost empty because while the properties were built the jobs did not come. Around the world there are other areas where despite population growth for different reasons parts and urban areas are deserted.
In London and the area around at the moment property prices have rocketed. One key reason for this is that along with other money slushed into the market is large scale buying by almost any and every money moving rich person taking advantage of the welcome they are given with no questions asked.
There is a slight downside to this. It is that very many of these people do not register their properties. Also, they are reluctant to pay much, if any, taxes but cannot be found because our welcoming institutions allow them to hide away their titles to wealth and property.
It could well be that if the inward flows of money continue to accelerate the amount of property in London, much if it unused and most of it not paying any taxes or charges means that Councils and others can no longer to fund services.
So values that put property beyond any ordinary people, many left unoccupied, declining or absent services and the inability of the authorities to identify ownership or responsibility could lead to a gradual attrition and then collapse of population.
Key to this is the failure to ensure the registration of property, and to know the identity of owners, users and others which means no action can be taken. If this continues then what starts as a cyclical decline could keep going down.
At least the Underground will be less crowded, if it is running.