A 90-year-old lesbian who was branded 'undesirable' and kicked out of the US Air Force has finally received an honourable discharge after a 60-year wait.

Helen Grace James, originally from rural Pennsylvania, was expelled by superiors after they discovered her sexuality during an undercover operation in 1955. Since that time she has battled for justice over her treatment. Lawyers for Grace issued a legal complaint on 3 January alleging the only reason for her dismissal was because she was a lesbian.

On January 17 she received official confirmation of her new status by mail, putting an end to an ordeal that had overshadowed her career for over six decades.

"I'm still trying to process it," she told NBC News. "It was both joy and shock. It was really true. It was really going to be an 'honourable discharge.'"

James joined the force as a radio operator in 1952 and worked her way up to crew chief at Roslyn Air Force base, New York, and received commendations for her excellent performance during that period.

However, her career came to an abrupt halt one winter's evening in 1955. According to James, intelligence agents at the Office of Special Investigations (OSI) followed her into a wooded area near Hampsted Harbour in Long island where she was meeting a female friend. After reaching into the back seat of her car for a sandwich, her car was raided by officers wielding flashlights.

The sting was part of a wider campaign by authorities to drive out homosexuals and 'un-American' behaviour from the military during the 1950s, known as the 'Lavender Scare'.

A few days later the agents returned to her base and interrogated her. They insisted she sign an official document outlining their version of the incident or face having her sexuality outed to her family. Not willing to face this, James left the US Air Force without severance pay or other benefits.

She subsequently moved to California and has lived there since, paying for her own education and making a new career as a physical therapist. She now runs her own therapy practice in Clovis, western California.

In the 1960s, and with help of an attorney friend, she was able to have her legal status changed from 'undesirable' to 'general discharge under honourable conditions', but was still not entitled to full veteran rights such as insurance and a military burial.

"It will make me feel like I've done all I can to prove I am a good person," she told NBC News on Tuesday, "and that I deserve to be a whole civilian in this country I love."

James says she is overjoyed at the new status change and says it recognises her "job helping to take care of the country I love".

"The Air Force recognises me as a full person in the military," she said.