Nicholass talk to Danny about people identifying mysterious people is taken from the Metropolitan Police Forces Street Smarts section, with all the points Angel brings up being taken straight from the manual, including wearing large jackets and having your cap brought down to obscure your face. The rest of Angels pronouncements, including that Police force is too aggressive, road accident implies theres no-one to blame and Doris Thatcher being a gender-neutral police officer rather than a police woman (even though Danny's seen her bra) are also true guidelines.