For the people who have never been over to dinner tell them they'll need a keycard to get to the house, only welcome them when they get to the kitchen. You'll only bother to go and meet your regular friends at the front door.
For your friends coming from Washington tell them you are having dinner in your luxury W1 five bedroom apartment with great views over Hyde Park. When they arrive tell them that because only two other friends are coming you are going to a rented garage in Brixton.