Nick Griffin's invitation to a garden party this afternoon at Buckingham Palace has been withdrawn, the Palace citing fears that he was using the invitation for "overtly political purposes".
In a statement, Buckingham Palace said: "This in turn has increased the security threat and the potential discomfort to the many other guests also attending."
It continued: "The decision to deny entry is not intended to show any disrespect to the democratic process by which the invitation was issued.
"However, we would apply the same rules to anyone who tried to blatantly politicise their attendance in this way."
Griffin was due to attend with his fellow BNP MEP, Andrew Brons. The invitation was to all MEPs, and according to the BBC, Brons, along with Griffin's wife, Jackie, can still attend.
Griffin's decision to accept the invitation, despite his previous assertion that his attendance would "embarass" the Queen, has been widely criticised, not least by James Macintyre in a blog earlier today.