We do know as he has said he used it everyday at the AO for at least 2 years and frequently in the USA
I know, but its use outside of hospitals, NHS and private, is banned throughout Europe. Of course, where's a will, there's a way ...!
Boris will talk, he cannot help himself it will come out at sometime.
I wonder what else will come out - like the full truth about his 'private issues' this year.