OK, $FamousPerson shows up at reception asking for an employee who has recently been escorted off the premises with their possessions in a black plastic bag (been there, got the video and t-shirt). You sort of know that random $FamousPeople showing up is part of $BusinessAsUsual. You have just realised that you have apparently no procedures whatsoever for booking appointments for personal visits to the building (e.g. popping something on a corporate Google calendar or Outlook).

So, you get $HighRankingPerson - preferably one with good empathy and small talk skills - to meet $FamousPerson, explain that, unfortunately, there has had to be a change of plan today. Meanwhile $TrustedPersonalAssistant has Googled $FamousPerson, worked out likely food preferences and made contact with $FamousPerson's PR people/publisher/agent/whatever. Nice restaurant booked for lunch. $FuturePlans discussed over (rather good wine | excellent smoothies | extremely expensive vintage cheese and crackers | exceptional artisian toast). Limousine booked to get $FamousPerson back to airport in time for trip home.

Not rocket science is it really? (I speak as one who has been told to F$$k Off by Royalty).