I've never been to a Royal garden party, and I'm not sure if you have either. The principle is clear though - they're an opportunity for the Queen to meet and thank those people who have made a significant contribution to their country and their community.
Obviously the great and the good get invited. But so do thousands of ordinary hardworking Britons who have quietly but steadfastly done their bit to improve our society.
Nick Griffin is not one of those people.
He's a criminal, with a conviction for incitement to racial hatred. He's a racist, who said last week that black Britons, including footballers David James, Sol Campbell and Rio Ferdinand could never be British. Griffin's also got some pretty nasty friends.
A couple of weeks ago the Mirror exposed his meeting with Don Black, a former Grand Wizard of the Ku Klux Klan banned from the UK on grounds of national security. And last month he sent his Deputy Simon Darby to meet up with Roberto Fiore, a man convicted for his links to the Armed Revolutionary Nuclei terrorist group responsible for the Bologna railway bombing, which killed 85 people, including two British tourists.
You'd think on security grounds alone, there would be questions about the BNP leader gaining entry to Buckingham Palace. But he is set to sneak in as a guest of BNP activist Richard Barnbrook, who is a member of the London Assembly.
Griffin himself obviously can't wait to crash the party. As the editor of the BNP magazine said yesterday: "The Palace garden party publicity stunt is reaping 100 times more attention than we had envisaged."
He certainly doesn't want to go so he can pay his respects to the Queen or her family. Griffin has branded Prince Charles a traitor because "he has made known his desire to represent people of all faiths and races". Mark Collett, the BNP director of publicity, was filmed saying: "The Royals have betrayed their people. When we're in power they'll be wiped out." There's a little part of me that would quite like Nick Griffin to meet the Queen.
Given Her Majesty is head of the Commonwealth, I'd like to see him explain his party's policy of rounding up all her black and Asian subjects and removing them from the country. I'd also like him to meet Prince Harry, recently returned from Afghanistan where he fought alongside the Gurkhas. When asked about the Gurkhas' campaign to stay in the UK Griffin responded: "Our policy position is the country is full. No more immigrants."
But though I'd love to watch Griffin squirm defending his hateful agenda it wouldn't be much fun for the other guests. Imagine you're a local community or charity worker. You've received an invite to the Palace. You put on your best dress or suit. You arrive, possibly with your elderly mum or dad on your arm. You feel proud.
Then you walk on to the Palace lawn, and who's standing in front of you. Nick Griffin. Racist. Criminal. Imagine how you'd feel. If you're black. If you're Jewish. If, unlike Griffin, you have hope, rather than hate, in your heart.
I've heard all the arguments. He's got a right to attend. His views may be controversial, but you can't censor him. Don't make him a martyr. Yes Nick Griffin's got rights. The trouble is, if he got his way those rights would be removed from millions of British citizens who don't have the same colour skin as him.
His views aren't just controversial. They're so extreme they have lead to his conviction in a court of law. A martyr? Because he might be denied a cup of tea and a cucumber sandwich? It's 70 years since Nazi boots first marched into Poland. People fought, and died, to prevent those same boots marching across the lawn of Buckingham Palace.
Some of those who lived through that struggle will no doubt be there on July 21. They have earned their invitation.
Nick Griffin has not.