This practice comes through training. Security patrol service in London has the precedence of training the guards in most efficient way. Guards are equipped with the required defense machinery and are efficient enough to use the weapons as needed. Moreover, a rigorous training program makes them able to handle all sorts of unforeseen circumstances.
Please read the originial post here: https://troocker.com/blogs/25743/Top-three-benefits-of-engaging-the-assistance-of-a-security