Fog lights
A survey investigated the effects of keeping your fog lamps on all the time has just been released and the results are far from pleasant.

It was found that over the last year 300,000 accidents were caused because of fog lights being used despite no impairment in visibility. To make matters worse, research has found that nearly three million drivers are happy leaving their fogs on all the time.
21% of drivers revealed they drove with extra illumination because their standard headlamps weren't deemed bright enough, while 14% of those surveyed admitted to using their fogs for purely cosmetic reasons.
Furthermore, 22% of 18-34 year olds claimed they appreciated the extra illumination for aesthetic reasons. Compare that to the 3% of 35-54 year olds who admit to the same crime.

And a crime it is. Using your fog lights in any situation other than when your visibility is down to 100m or less is an offence. Get busted and you'll find yourself with a £30 fine. Apparently London drivers are the worst for this offence.
The Highway Code dictates that drivers shouldn't:

Use any lights in a way which would dazzle or cause discomfort to other road users, including pedestrians, cyclists and horse riders

Use front or rear fog lights unless visibility is seriously reduced. You must switch them off when visibility improves to avoid dazzling other road users

The survey said "Fog lights are designed for a very specific purpose – helping drivers to see and be seen when visibility is severely reduced. Misusing these lights has the effect of dazzling and distracting other motorists and causes a staggering number of crashes, as evidenced by research. If you can see further than 100m (roughly the length of a football pitch) then your fog lights should remain off".

It's also a case of common courtesy. Don't be a fool and blind your fellow motorists. Time to get your common sense head on Britain!!