Operational errors by the police led to the security breach at Windsor Castle, according to a report accepted by the home secretary.

David Blunkett was told that a catalogue of human errors allowed a man dressed as Osama bin Laden to gate crash the 21st birthday party of Prince William in June.

The independent report into the incident revealed Aaron Barschak triggered seven alarms and was caught on CCTV but was ignored by officers on duty.

Blunkett was forced to give an official apology in the Commons following the incident which happened despite the high level of alert because of the threat of a terrorist attack.

Following a review, Commander Frank Armstrong made 28 recommendations to improve and enhance security measures.

His suggestions were backed by Met police commissioner Sir John Stevens who also called for new legislation that would make intrusion into royal premises a criminal offence.

Although cautioned, Barschak is unlikely to face criminal charges.

Eight officers are facing disciplinary charges and the police chief in charge of security at Windsor Castle has been removed from the post.

Embarrassingly, the report also reveals that the party's organisers refused to give a guest list to the police until shortly before the event began - apparently because they thought it would be leaked to the press.

"Overall the report demonstrates that no single individual was entirely to blame - the compounded sequence of events that occurred combined operational deficiencies with elements of poor professional judgement," said Sir John.

"This incident has served as a grave wake-up call and we must now ensure the right steps are taken so that security cannot be breached in this way in the future."

The home secretary described the report as "comprehensive and constructive" and vowed to avoid another serious breach of security again.

"The commissioner has assured me that significant lessons have been learnt from this incident and that the important service that the police play in protecting the royal family will be further improved," Blunkett said.

"Commander Armstrong's recommendations provide a sensible foundation on which to develop sound policies for enhanced protection in the future. this was a potentially highly threatening breach of security.

"We will learn the lessons from the incident and do everything we can to prevent such breaches happening again in the future."

Liberal Democrat home affairs spokesman Simon Hughes described the incompetence of the policing at Windsor as "astonishing".

"If Mr Barschak could walk through eight alarms and five CCTV cameras at Windsor Castle, so could a terrorist. The police must learn the lessons of this incident quickly, and if necessary review security at other high-profile UK buildings. This must not happen again," he said.