Possible Clues:

• Bloody stupid fellow who's left school
• No longer at school and possibly retired
• One in an exclusive network
• One of the inner circle
• A kind of network man?
• Familiar mode of address for ex-pupil?
• Sounds like water mark is out-of-date for school-leaver
• Bloody stupid former pupil
• Address that's familiar for a school leaver?
• Bloody awful type from former school