Arorat you sure you need winter tires in London right now? From what i see the temp hasnt fallen below 7c yet and we are already mid november! If i remember correctly, in 2 years of driving in london i felt i only needed the winter tires once!
As usual you've missed the point by a mile
The winters in recent times (the last two years excepted) have been exceptionally mild and snowless. This by all accounts is not typical of the UK. You probably lived here for 2 years when snow was uncommonly rare. This is not what British winters are usually like.
At the very worst the people who've bought winter tyres this year will have another set of tyres which will be sharing the tyre wear duties. Which means that they'll just be waiting longer to wear out their summer and winter tyres than if they just had one set of tyres. One point which I make all the time and which gets constantly ignored for some reason, is that summer tyres wear QUICKER than winter tyres when it's cold. So buy buying winter tyres you may actually be better off financially.
It's also about being prepared for what may happen. The last two winters HAVE been harsh at times and have resulted in less than ideal driving conditions. Sure the conditions have been rather unwintry so far. But last year was quite the same and I remember wondering whether I'd put my tyres on a week or two early and then it all started to kick off and I was laughing...... Some people at work had to
Worst case - People have spent a bit more money now, but it'll pay off because it'll just be longer till they need to put another set of tyres on the car.
Best case - it snows heavily = WIN