Operation Sceptre is an operation from the Metropolitan Police started in July 2015 that tackles knife crime in London. Not only does it target people who use and carry knives, it also targets those who supply knives and importers of them.
During the sixth phase of Operation Sceptre they conducted 5971 weapon sweeps and 700 test purchases form shops that sell knives. 793 arrests were made due to stopand searches and 339 weapons off the streets. Over all Operation Sceptre reslulted in 2294 arrests (473 where for possession of weapons) and taken 1453 weaponsm off London's streets. As well as this they work with Words 4 weapons a charity with 30 surrender bins to put knives in around London.
My source is the Metropolitan Police website