No further action is to be taken against the intruder who managed to gatecrash Prince William's 21st birthday party at Windsor Castle, according to Scotland Yard.
Aaron Barschak expressed regret over the incident
Self-styled "comedy terrorist" Aaron Barschak, 37, jumped on stage dressed as Osama bin Laden and reportedly kissed the prince on both cheeks, before being arrested.
The decision to take no further action against him was made following advice from the Crown Prosecution Service, said police.
Mr Barschak, who has now been released from his bail conditions, said he was shocked and surprised by the announcement.
The comedian got into the 21 June event by climbing a tree, then jumping on to a wall and clambering to a terrace.
Once inside, he persuaded police officers that he was a legitimate guest and was able to mingle with other revellers
Among the guests were the Queen, Prince Charles, Prince Harry and Camilla Parker Bowles, as well as William's friends from St Andrews University in Scotland.
Scotland Yard apologised for the "wholly unacceptable" breach of security and the chief inspector who was in charge of security at Windsor has been moved to another job.
A total of nine officers have also been told they are under investigation as part of the inquiry into the security breach.
Aaron Barschak was dressed as Osama Bin Laden
Home Secretary David Blunkett said he was "deeply concerned" by the security breach in a statement to the Commons.
Speaking after the event, Mr Barschak said he "absolutely" regretted the whole incident.
"I did it as a publicity stunt and it's all come crashing down," he told the BBC.
Mr Barschak has a history of sabotaging high-profile media situations and briefly stealing the limelight.
His recent victims have included London mayor Ken Livingstone, comic Graham Norton and Monty Python's Terry Jones.