A report into the breach of security during Prince William's 21st birthday party has criticised police for a "series of errors" on the night.
Aaron Barschak has apologised for the stunt
Comedian Aaron Barschak set off six alarms and appeared on CCTV several times without sparking a response when he gatecrashed the party at Windsor Castle, it found.
The report - by Commander Frank Armstrong of the City of London force - gives 28 recommendations for changes to the way the Royal Family is protected in future.
Among them, it calls for legislation to create a new offence of trespassing on royal or government property.
No particular officer is singled out for criticism over the handling of the royal party on 21 June.
But the chief inspector in charge on the night has been moved to another post, and eight are under disciplinary investigation.
Mr Barschak himself said he had no regrets about his actions and was happy his antics could lead to improved security around the Royal Family.
He also said the police should not be blamed and he was glad no officers were going to be sacked.
"There isn't anybody in the world who isn't guilty of complacency as a result
of routine... they'll probably be extra vigilant now," he said in a press conference following the report's publication.
But on the new trespass law idea, he said: "Personally I don't think that would serve to deter somebody who is out to harm a member of the Royal Family."
The Commissioner of the Metropolitan Police, Sir John Stevens, said his force had been "devastated" and given a "grave wake up call" by the report's findings.
Home Secretary David Blunkett said Sir John had assured him "significant lessons" had been learnt from the incident.
The important role of the police in protecting the Royal Family would be "further improved", he said.
But Shadow Home Secretary Oliver Letwin said the security operation had been a "shambles".
And Liberal Democrat home affairs spokesman Simon Hughes said the "sheer
incompetence" of the operation was astonishing.
The report highlighted three key errors in the police coverage of the party.
It said there had not been enough police on duty.
The working conditions, training and resources in the police control room at Windsor
were "wholly inadequate".
And the chief inspector in charge of security had left the event an hour before Mr Barschak's break-in.
Mr Armstrong said the party had been dealt with as a private event with low-key security, when in fact it should have been treated as a high-profile event with top security.
"Certainly this event taking place in a post-11 September world should have warranted the highest level of security," he told BBC News.
"There should have been sufficient resources, and this event should have had oversight by a senior Metropolitan Police officer.
"Unfortunately that didn't happen."
Mr Barschak - who was dressed up as wanted terrorist leader Osama bin Laden - first set off an alarm when he climbed a tree and scaled the perimeter wall, but this and several others were ignored.
In addition, one CCTV view had been blocked by catering contractors' vehicles.
In his bizarre costume and beard, police at the royal party assumed Mr Barschak was just another guest in fancy dress and let him in to the party.
The comedian was only arrested after he had interrupted a speech by Prince William, and kissed him.
Following the stunt, attention was drawn to the potentially disastrous consequences that could have followed if Mr Barschak had been a terrorist.
All senior members of the Royal Family apart from Prince Edward had been present at the party.
Mr Barschak, 37, from Golders Green, north London, has been told he will not be prosecuted over his actions.