The reason why the Queens are very - ahem, controlling with regard to the ExtraOrdinary Wizards is because they are in charge of the safety of the Castle, and as such, they have to keep an eye to the actions of the Wizards, as they are often marked by an appalling lack of safety policy. - Septimus Heap.
Marcia, after reading Septimus's note saying that he is now Marcellus's apprentice, says that it had his signature, which was a seven. This makes sense if you remember that Septimus is a Magical Seventh Son. - Lord Of The Internet.