In shock, the girlfriend who was sure Tom would go free

Today the British press and expectant crowds packed Nairobi's High Court to hear final judgment on Kenya's most high-profile celebrity inmate.

In a case that has gripped the nation, Old Etonian Thomas Cholmondeley, 40, the great-grandson and heir of Lord Delamere, the colonial-era progenitor of Kenya's most famous white family, arrived in court this morning to learn his fate after being locked up for three years in Nairobi's notorious Kamiti Maximum Security Prison.

After reading out his marathon 320-page verdict, Judge Muga Apondi found Cholmondeley guilty of manslaughter, a crime that in Kenya typically carries a life sentence.

The judge announced that Cholmondeley had fired the shot that had killed Robert Njoya, 37, a poacher who he had come across on the family ranch in May 2006. To gasps from the gallery, the judge said that Cholmondeley would be sentenced on Tuesday.

In court to hear the shocking verdict was Sally Dudmesh, 47, the elegant and long-suffering girlfriend of Cholmondeley. She was devastated.

In the days before the trial, she had told the Evening Standard that there was only one outcome - "Tom's acquittal" - that she had been prepared to contemplate.

Speaking from the Ngong Dairy, her stunningly gorgeous house in Karen, Nairobi, at the foot of the Ngong Hills - the same house that was used as Karen Blixen's home in the film Out of Africa - Dudmesh had said: "It's incredibly stressful. I am just trying to cope with this hour by hour, day by day. I'm the person who has visited Tom in prison once a week for three years, who has stood by him, supported him and fought for him. I have always believed in his innocence."

She recounted how three years ago, almost to the day, she got an urgent text from Cholmondeley to say he had been taken into police custody. A black poacher, Robert Njoya, had been killed on his family's 56,000-acre estate in the Great Rift Valley and Cholmondeley was the prime suspect.

The killing came a year after Cholmondeley, a controversial character in Kenya, had been cleared of shooting and killing an undercover black game warden, Samson ole Sisina, arguing that he had shot him in self-defence.

In the poacher case, Cholmondeley admitted firing his Winchester bolt-action rifle but maintained that he aimed only at the poacher's dogs.

His lawyers had claimed that his rally-driver friend, Carl Tundo, had also fired his pistol in the mêlée. Two lay assessors had concluded, in March this year, that there was insufficient evidence to decide which gun had delivered the fatal shot and had handed down a verdict - which is influential but non-binding on the judge - of "not guilty". As it turned out, the judge decided otherwise.

Close to tears as she had recounted these events, Dudmesh, the daughter of wealthy English tobacco farmers, who spent her childhood in Pakistan, Mauritius, Ghana and Yemen, made an honest admission.

"If I'd known Tom would be locked away for three years, that it would mean three years of my life, I don't think I'd have agreed to stand by him," she says. "For me, it feels like I've been in prison, too. I'm really suffering. This is beyond what a human being can tolerate."

A jewellery designer whose creations sell for up to £2,000 apiece, Dudmesh has lived an intensely privileged and tortured life.

Although her lifestyle is enviable, involving safaris, trips to souks and living with the Masai for months on end, she was also famously part of a hard-partying expat set, four of whom are now dead. They prided themselves on living fearlessly and indulged in wild socialising that carried on long after it had been exposed in books such as White Mischief.

"Outsiders see my lifestyle as charmed and, yes, it can be magical waking up to the animals and the big skies or under the stars at night, but you pay such a big price for the beauty," Dudmesh had reflected. There is that sense of wildness here, it's a kind of cowboy country. This attracts people who don't quite fit in with the rules and structures of England and that's why in the past you often used to find the black sheep of families settling here."

Two of her previous lovers were murdered: Tonio Trzebinski, 41, a rugged London-educated artist and aristocratic adventurer, was mysteriously shot through the heart in Nairobi in 2001, and Giles Thornton, 32, another wild and charismatic British artist, was shot dead in Kenya three years earlier. She was not involved with either man at the time of their deaths.

She also had a relationship with Carlos Mavroleon, 40, another Old Etonian adventurer who went off to fight with the Afghan mujaheddin and was found dead from a heroin overdose in 1998 in his hotel room in Peshawar on the Pakistan border. And her best friend was Emma McCune, the legendary aid worker who married a Sudanese guerrilla commander and, pregnant, was killed in a suspicious car accident on her way to a party at Dudmesh's house in 1993.

Dudmesh had worried that Cholmondeley - the only white man and the longest-serving remand prisoner at Kamiti - would also die. Built for 1,400 prisoners, Kamiti today houses 3,600 inmates in conditions of unimaginable squalor.

Sixty years ago in Kamiti the British tortured Kenyans suspected of involvement in the Mau Mau rebellion, including Barack Obama's paternal grandfather, Hussein Onyango Obama, who later told his family that he had been "whipped every morning" and that his testicles had been "squeezed with metallic rods".

Although Cholmondeley has not been physically tortured these past three years, Dudmesh said he has been kept in appalling conditions in the punishment block used for political prisoners.

Indeed, he has been held in the same cell that once held Raila Odinga, the Kenyan opposition leader and Prime Minister currently in a coalition government with President Mwai Kibaki. "It's a damp, greasy, tiny cell, 6ft by 9ft, and it's especially hard for Tom who, at 6ft 4 ins, is taller than the cell is wide," she said.

Over New Year, continued Dudmesh, she became particularly concerned when Tom's weight dropped alarmingly and he lost four inches around his waist following severe food rationing by the authorities.

There had been a high-profile incident, reported in the Kenyan press, in which some inmates concocted an illicit brew - made of turpentine and thinner from the prison workshop - for a Christmas celebration which turned tragic when two prisoners died and three went partially blind.

Embarrassed by the deaths, the prison authorities responded in typically draconian fashion. Food parcels that visitors such as Dudmesh regularly brought in on their weekly visits were banned and all inmates were placed on minimum rations.

"For a few weeks Tom was on a diet of nothing but rotting spinach, which he said was like eating compost," she said.

"It was tasteless and had no nutritional value and he couldn't keep it down. He lost masses of weight. I was worried about his physical condition and strength but even more disturbing was the impact mentally. He went to a very low and dark place. He lost all motivation to carry on. There were times when I wondered whether he could survive the next day."

Asked how Cholmondeley's parents, the 5th Baron Lord Delamere and Lady Delamere, have managed, she said: "It's been awful for Ann, Tom's mother. It's been very difficult for her to cope with her son being in prison for so long. She's been ill. She's had shingles from the stress."

To add to the pressure, the British press have been camping on her doorstep, Dudmesh said. "I've held them off until now but we've never seen anything like it."

Indeed, in an uncanny echo from the past, the last white Kenyan case to attract such international attention involved Cholmondeley's step-grandmother, Diana.

Before becoming the third wife of the fourth Baron Delamere in 1955, Diana was the mistress of the infamous playboy Earl of Erroll, and the wife of Sir Jock Delves Broughton, the man acquitted of murdering Erroll in the 1941 trial.

The events were dramatised in the 2001 film White Mischief, starring Greta Scacchi.

Dudmesh moved to Kenya after falling in love with the country when her parents gave her a trip there for her 18th birthday. She first met Cholmondeley on a trek in Mongolia in 1998.

At the time she lived a "highly sociable lifestyle" travelling the world in search of exotic materials for her jewellery, and he was newly married to Sally Brewerton, a British physician working for Doctors Without Borders.

Tom had met his wife in hospital after being attacked in the Masai Mara by a buffalo that had gored him, its horn piercing his thigh, ripping through his knee and coming out at his ankle.

"It was another seven years before Tom and I got together," she said. By then, Cholmondeley and his wife had separated but had two sons, Henry and Hugh, now aged nine and 11, who live with their mother in Sussex. She said that Cholmondeley's wife had asked her to arrange a camel safari for him and that was when their relationship took off.

"It was a scandal," she admitted. "But that year, we had a year of total bliss. It was like we'd found our other halves. Then this killing happened."

The shooting of the poacher provoked public outrage and brought long-simmering racial tensions to the boil.

To Dudmesh's dismay, the white community turned against Thomas, whom they saw as a trigger-happy throwback to the discredited days of the Happy Valley set.

His great-grandfather was infamous for riding his horse through the Norfolk Hotel in Nairobi and shooting the lights out as he jumped over the tables. The imprisonment of Cholmondeley symbolised the declining power of wealthy white-settler families.

"People have this view of Tom that he is an arrogant, aggressive person but he's misunderstood. He's actually very quiet and passive," said Dudmesh.

On Monday she had made what she fervently hoped would be her last visit to Kamiti prison. "I know Tom is innocent and I believe in justice," she said. "Like Tom, I am living hour by hour. I just need it to end, and to end well."

But sadly, as we discovered today, there was to be no happy ending.