Possible Clues:

• Separated, yet up for coming round to social event
• 1773 Boston gathering
• Famous celebration in Boston - no alcohol
• The Mad Hatter's get-together
• Social occasion but, contrarily, drinks not included
• Bound to go topless gatecrashing provocative though genteel gathering
• Separated, but about to come round for social event
• The Mad Hatter held one
• Food and drink at P separated but turned around
• Social occasion in Boston: tipping in the main was dutifully observed