If you’re a London retailer, the chances are that you’re sick of having feral youths overrun your store, shoplifting and intimidating loyal customers. It’s also likely that you’ve wondered whether these kids are just harmless hoodies with no manners, or members of these so-called “gangs” who engage in criminal activity – and could well be armed.

Well now, there’s a website that could just help you judge. Created and endorsed by former gang members themselves, Gangsoflondon reveals the territory, history and characteristics of over 100 of London’s most notorious gangs, with chilling names like The Blood Block and Kamikaze Krew. On the site there are maps demonstrating the turf warfare and local rivalries – and frequent jibes at how ineffectual the Police’s own surveys have been.

The site suggets that Wandsworth and Merton have the fewest gangs, “owing to less deprivation”, and that Hackney and Tower Hamlets are the most dangerous. How does your postcode fare? Do you have a problem with aggressive teens in your shop? And how do you deal with them?