The prohibition on private cars makes little difference to those who want to view the lights anyway—waiting until dusk assures they are as twinkly as possible. Street lighting is also used extensively throughout the city during the season, so traffic problems aren't an issue.
The answer is yes, you can drive into London with Christmas lights.
London is one of many cities around the world that decorates its streets with festive illumination every year. The capital's display has become famous for its size and longevity - thousands of LEDs create a huge area of light sculpture that lasts for more than two weeks after Christmas Day. It's so popular that traffic tends to slow down at this time of year.
The history of street lighting in London goes back over 200 years. When gas was first introduced into Britain, it was as a means of lighting up the streets during night hours (because it was easier and cheaper to do so). Its main use remained as a source of light until electricity became available in the early 20th century. But even then, some people didn't switch over completely because it was felt that the old-fashioned appearance of electricity wiring was not acceptable for public spaces.
So the tradition continued of taking the darkness of winter and giving it form with lights.
Yes, it is true that we do not reach the "real night" stage of the night in the summer. After the sun sets, there are specific levels of light known as civil twilight that provide adequate light for the human eye to do most activities, although town and city lights will begin to illuminate. When actual darkness falls, this becomes astronomical twilight when only stars can be seen against the sky.
Civil twilight ends when moonlight, sunlight, or street lamps become bright enough to read a book by. At this point, you need artificial light to see anything at all. Nighttime comes much earlier in the summer than it does in other seasons because there's less daylight during those days in the summer.
The time of day has a huge effect on how dark it gets in London. In the summer, nights are usually very light thanks to the lack of clouds and darkness falling by about half past seven. But even at three in the afternoon, you'll still need artificial light to see anything.
London has some of the darkest cities in Europe, but surprisingly, it doesn't get that dark here in the summer. The city is lit up like Broadway at night, so you should have no trouble finding your way around.
If you are walking home from work or from an event at night, you should not be met by darkness. Problems with public transportation can arise in numerous cities. It frequently does not operate on time, is poorly maintained, and, in certain situations, is not adequately policed. You should expect these problems to be even more acute in larger cities where there are more people trying to use the system.
It is safest to travel during daylight hours when you can see people around you. Avoid isolated spots after dark, whether they be streets, parks, or sidewalks. If you do find yourself in need of shelter, avoid blacktop surfaces unless you are sure no cars are driving past. Instead, look for a clear space under a tree or near some kind of cover.
Sweden has one of the highest rates of car ownership in Europe. This means that many areas are deserted after dark, so it is important to be aware of your surroundings. If you do encounter someone while out walking at night, remain in the street until you know that it is safe to cross. Cross only at marked crossings or at intersections with red lights. Never cross against a red light. If a car approaches but does not stop, continue walking back up the other side of the road until you are sure that it is safe to cross.
In Sweden, as in most countries, the crime rate is generally low.