The Right Honourable Thomas Cholmondeley plonks his gangly frame in a battered armchair as if he was in an Eton common room rather than Kamiti Maximum Security Prison. A rare coincidence of water and electricity means he has had a hot shower for the first time in weeks.

“I’ve washed my hair and had a good shower and things always seem better then,” he says, beaming his greetings around the shabby prison warders’ office, where he is allowed to meet visitors.

It is more than two years since Mr Cholmondeley, 40, was arrested and charged with murder after a poacher was shot dead on his family’s 58,000-acre estate. Mr Cholmondeley’s defence will finally begin today. His trial has dragged on endlessly, with suspicions that the prosecution is stalling for time in a case it cannot win.

The Old Etonian heir to the fifth Baron Delamere initially told police that he accidentally killed Robert Njoya while trying to shoot dogs that were bearing down on himself and a friend. He changed his story when detectives charged him with murder. They had investigated Mr Cholmondeley a year earlier for shooting dead a wildlife ranger, only to see the case dropped on the instruction of the Attorney-General. His defence has since managed to raise doubts that he fired the fatal shot. That has not stopped Kenyan politicians using the trial to whip up antiwhite sentiment in a country where land distribution remains a touchpaper issue.

The case has dragged on with a year-long legal petition, 38 prosecution witnesses and constant delays as the judge notes down evidence in longhand. Now Mr Cholmondeley, the great-grandson of the third Baron Delamere, who was one of Kenya’s most famous white settlers and the founder of the Happy Valley set, will give his side of the story. He is expected to read a nonsworn statement, a tactic which prevents the prosecution from a further opportunity to slow the trial by cross-examining him.

Life in jail has settled into a routine. “I get out of bed, do a little exercise, some yoga. We take a bit of tea together. Sometimes we play badminton,” he says. The rest of the day is spent reading or keeping a diary, which he hopes to have published.

A prison officer opens the door to the office and immediately apologises to “Mr Tom” before backing out again.

“I can tell you great stories, like the day we killed 22 rats in half an hour and we all went round with broom handles, like game hunters,” Mr Cholmondeley continues. He is putting a gloss on things. Friends say he often breaks down in tears during phonecalls home. “It is very dark most of the time,” he says. “The reason I don’t dwell on the horror of this place is that it’s almost a caricature. It is so horrific.”

His supporters are convinced that the judge will have no other option than to find him innocent of murder. The fear is that a second acquittal could prompt fresh unrest in a country where divisions over land and money were exposed during weeks of political and tribal violence earlier this year.

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