There's a whole DD guarantee system, you can cancel them at anytime. Gawd what load of hassle you must tolerate OG! My entire set up is totally automatic, a penny has never gone missing. It's a major chore for me if I do have to intervene at any time, thankfully that is rare.
If you do not use internet banking then that makes it much easier for a potential tea leaf to use your details to activate your internet banking without your knowledge, all they have to do is your SC/Acc, on every cheque, to set up for you, they just need to intercept one letter then they'll have all they need to pretend to be you. They will then supply their phone number and passwords/recognition data etc. Much better to do it yourself.