A leading ejector seat manufacturer based in Denham - prosecuted after the death of a member of the Red Arrows - put many pilots at risk over a lengthy period, a court heard.

Flight Lieutenant Sean Cunningham was fatally injured after being ejected from his Hawk T1 aircraft while on the ground at RAF Scampton, Lincolnshire, on November 8, 2011.

The parachute on the Mark 10B ejector seat did not deploy, and the South African-born airman fell 200ft before he later died in hospital.

Martin-Baker Aircraft Company Ltd – which has its headquarters in Lower Road, Higher Denham - admitted failing to ensure the safety of non-employees in connection with the 35-year-old's death at a hearing on January 22.

On Monday, Lincoln Crown Court heard how the company has already agreed to pay £550,000 in prosecution costs as a result of the guilty plea.

Although the company pleaded guilty, it disputes some of the allegations made by the prosecution.

Opening the case against the firm, prosecutor Rex Tedd QC said: "The defendant admits that the breach of duty was a substantial or significant cause of the death of Flight Lieutenant Sean Cunningham."

Mr Tedd said the company had a duty to "ensure none of the pilots" were exposed to a health and safety risk.

He continued: "The defendant accepts that the risk persisted for a long period.

"If the pilot was ejected from the Hawk aircraft, two shackles would not release from one another and would jam together and the main parachute would not deploy.

"The pilot would be several hundred feet in the air and there could only be one result of that, and that is the pilot's death."

In a statement released after the guilty plea, the company said: "It should be noted that this was an isolated failure relating to the tightening of a nut during maintenance procedures conducted by RAF Aerobatic Team (RAFAT) mechanics."

But the prosecution claims Martin-Baker Aircraft Company's position that Mr Cunningham's death was an isolated incident is "not accurate".

Mr Tedd added: "There was a risk to many pilots over a lengthy period. The defendant's failure was anything but isolated.

"Each pilot should have complete confidence in the ejector seat."

However, the court heard how the company had invented the ejector seat and "undoubtedly saved the lives of many pilots".

The firm describes itself on its website as a family-run business and "the world leader in the design and manufacture of ejection and crashworthy seats for nearly 70 years".

The court heard how Mr Cunningham's two greatest fears became a reality when he was ejected from the stationary aircraft.

Despite the Hawk undergoing a routine inspection in October, the pilot still fell from a considerable height and sustained injuries that were "unsurvivable".

Mr Tedd said: "Sean's two biggest fears in life were being ejected from an aircraft and the injuries that would be sustained, and dying at a young age. He was to tragically experience both of these."

"This tragic incident was the eventuation of the risk of the shackles jamming at low speeds."

The sentencing hearing is set to continue on Tuesday.