London is a relatively safe city. Violent crime isn’t as prevalent here as it is in other travel destinations, most likely due to the general lack of guns on the street (although the number of illegal guns in the UK has risen over the past few years). Few police carry guns, though you may well see armed police at airports, main railway and underground stations, government buildings and embassies, especially so if there could be a terrorist threat. Crime here is more likely to be of the thieving kind – pick pockets and bag-snatching – than it is to be of the violent kind so you shouldn’t ruin your vacation by obsessing over it. Thanks to the overabundance of CCTV cameras around the city, the police maintain an almost “Big Brother” presence on the streets.  

Like any other large city however, London has its fair share of dangerous suburbs with high levels of violent and drug related crime - however they tend to be well away from the central area of the city so it would be impossible to accidentally venture into one of these areas unless you were making a conscious effort to do so.

That being said, you should still use common sense and keep aware of your surroundings, especially at night. If you travel alone at night stick to well lit areas and busy streets, and be careful not to flash around large amounts of money or expensive mobile phones. Generally if it's your first time in London it isn't a good idea to travel alone late at night (after 11pm), as many areas outside zone 1 can become a lot quieter (and feel more threatening).

If you are using the Underground late at night for peace of mind jump in a carriage that has other passengers in it. It's not unheard of (but rare) for roving gangs of teens to assault solo passengers late at night! If you must use a cab use London black cabs or licenced mini-cabs (these can be booked by phone or visiting a cab office).  Never use an unlicensed minicab and never accept a ride in the street from someone claiming to be a minicab driver, they must be pre-booked.  Black cabs are heavily regulated and should give you much more protection.  Over the years there have been many cases of people being seriously harmed by people claiming to be minicab drivers.  Do bear in mind, though, that in any vehicle you hail on the street, only you and the driver know where you are.  You are much safer booking a car over the phone, and make sure that someone else knows where you are and what car you are in.

The common sense rule also holds true for women travelers. Don’t walk alone at night and know where you are going ahead of time.  It’s also a good idea for women to avoid cars hailed on the street if traveling alone. You should be perfectly safe in a controlled and registered cab, but if concerned call one by telephone to ensure that is not a fake, and make sure someone else knows what car you are in. Like in any major city, it’s not uncommon for solitary women to encounter unwanted comments from males, but on the whole it’s more likely to be innocuous (although irritating) than anything else. Use your head and trust your instincts.  If something doesn’t feel right, then seek outside help.  If possible, try not to look too much like a tourist. Carrying a guidebook in hand on buses and tubes clearly identifies you as one, thereby making you vulnerable. To a potential mugger, this is a clear indication that you are unaware of your surroundings.

If you do find that you need the police, dial 999 or 112 from any land-line or mobile.