Who is to blame for latest royal security blunder?

The latest lapse in security will pose the biggest challenge yet for Brigadier Jeffrey Cook who is only weeks into his new job as overall chief of royal protection.

Brigadier Cook, 49, was appointed to his new role of Director for Security Liaison following recommendations from a Security Commission report which called for wider checks on job applicants, guests, visitors and contractors with access to royal residences.

His appointment followed a series of major blunders.

They involved the undercover Daily Mirror reporter who got a job as one of the Queen's footmen for two months. Last June "comedy terrorist" Aaron Barschak gatecrashed Prince William's 21st birthday party at Windsor.

When he went for his interview with the Queen's most senior aides at Buckingham Palace, Brigadier Cook admitted privately he was a little nervous. But the father of two did not let it show, friends say.

When one of the long-serving courtiers tried to tell him the "job description," Brigadier Cook stopped him in mid sentence.

"He simply told his interviewers what he thought was the job description as he saw it.

Afterwards he reflected on it and thought he may have blown his chances, but clearly they liked his attitude," a source said.

"He is not used to failure and this will make him even more determined."

Brigadier Cook, a trained parachutist, was awarded the Military Cross during his time in the Balkans.

After the Barschak fiasco Metropolitan Police Commissioner Sir John Stevens was ordered to improve security at all royal residences. The Barschak incident put Commander Peter Loughborough, head of the Royal Protection Department, under pressure to resign.

But the Old Etonian kept his job despite an internal police investigation which Sir John described as "disturbing reading". Mr Loughborough is still commander of the department and in "day to day" operational charge of security.

He liaises with Brigadier Cook on security matters who in turn reports to the Queen's private secretary, Sir Robin Janvrin.

After the Barschak affair five officers, including an inspector and a sergeant, were disciplined.

Commander Loughborough kept his job because it was thought that the roots of many of the inadequacies in Windsor security pre-dated his time in charge.

Brigadier Cook's appointment was approved by the Queen last month, before the publication of the Security Commission report.

His Army salary was believed to be between £75,000 and £80,000, with a pension of up to £35,000.

The Brigadier was responsible for initial selection and basic training of soldier recruits. He was also responsible for the Army Foundation College at Harrogate and the Army Technical Foundation College at Arborfield, Berkshire, as well as recruit selection centres up and down the country.