by the BBC's Gillian Ni Cheallaigh
at Scotland Yard
The castle was the scene of an amazing security breach
An investigation into the security breach at Prince William's 21st birthday party has found mistakes made by police partly to blame.
The report into the incident reads like a catalogue of errors, from the first moment Aaron Barschak climbed over the wall at Windsor Castle.
Once inside he activated as many as seven alarms and was visible on CCTV as he moved around.
None of this triggered a police response and the police control room at Windsor has come under severe criticism.
That is just one area highlighted for improvement, out of 28 recommendations made by the senior officer from the City of London police, Commander Frank Armstrong, who carried out the inquiry.
Other areas to be targeted are the pre-planning of all royal events, public or private; and the level of communication and cooperation between the Metropolitan Police and other agencies involved in royal security, such as Thames Valley Police and the Army.
Also among the recommendations is a proposal for a new law that would make trespassing on royal property a specific crime, thus introducing a new element of deterrent that currently does not exist.
The Metropolitan Police Commissioner, Sir John Stevens, has described the report as "devastating", saying the force unequivocally accepted its findings and recommendations, and was making no excuses.
He said the incident had been the result of operational and human failings, and simply should not have been allowed to happen.
He also said a more professional approach was needed.
Aaron Barschak tripped several alarms in the castle
Although human error was pinpointed as being at least in part to blame, none of the officers involved has been singled out for blame in this report.
Commander Armstrong said there had been "no witch hunt".
Eight police officers are currently being interviewed as part of an internal disciplinary process, and could face disciplinary action.
The report in its final recommendation hopes that this event will act as a catalyst for a complete review of security at all royal residences.
The Queen and the Royal Family have been advised of the report's findings and recommendations.
According to Scotland Yard they have approved all the changes.
Scotland Yard says the changes are being "energetically" implemented and more than half have already been brought in.