IT would be funny were it not so very serious. We live in a world which fully expects another terrorist atrocity at any moment; in which arms dealers living on suburban British estates are caught preparing to sell rocket launchers to fire at Presidential aircraft from the back of motorbikes.

And yet a comedian in an Osama bin Laden outfit and a peach-coloured dress manages to gatecrash Prince William's fancy dress birthday party, wander unchallenged round Windsor Castle for an hour, and stand next to him on stage before nipping off to the bar to order champagne.

In the process, he sets off seven intruder alarms and is spotted five times on security cameras.

Meanwhile, the senior police officer in charge of security goes home early before the party has barely started.

You simply couldn't make it up.

Aaron Barschak might as well have run round Windsor Castle with a large sign declaring "I'm a terrorist". The chances are that he still would not have been arrested.

Luckily, Barschak is not a terrorist. He is a comedian, but nowhere near as big a comedian as the clowns on security watch that night.

Of course, in the light of all this, there has to be an overhaul of security concerning the Royal family. The police have shown they are not up to the task and Army experts must take over.

But it must go much deeper than a change of guard. It must be accompanied by a complete change in attitude - and that includes the Royals themselves.

The fact that the names of invited guests had only been given to police on the day of the event exposes glaring failures within the Prince of Wales' household. It shows that complacency is dangerously rife. How could adequate checks possibly be put in place?

Irresponsible though he was, Aaron Barschak has done the Royal family a great service - by laying bare the shambles of their security arrangements.