So that's what I did. Because they don't give this scheme a name, it's hard to talk reception staff about exactly what it is you want to opt out of. They were very understanding, but left me with forms to opt out of the Summary Care Record which is not the same thing. Even if you've already oped out of the Summary Care Record you must still opt out of this.
An email to the practise manager did the trick though. I asked by what mechanism they achieve the opt out, as it all seem very vague. A very helpful and prompt response explained that a change has been made to the access conditions of my record in System One (the monolithic care record system) such that it can't be used for this purpose.
All of which is great. But this scheme should clearly be on an opt in basis.