|The judge told Harris: 'You designed your life to be close to boys'|
Simon Harris, 55, from Herefordshire, was convicted of three indecent assaults, five sexual assaults and four counts of possessing indecent images of children in December last year.
The offences involved five children - one was aged just nine.
At his eight-week trial at Birmingham Crown Court, jurors heard Harris would cruise the streets of Gilgil and lure vulnerable boys into his Land Rover with the promise of education, food and money.
He would take them back to his home, known as the Green House on the outskirts of the town, and sexually abuse them.
The court was told that some were threatened with death if they told anyone.
Judge Philip Parker QC said Harris was obviously "intelligent" and "charismatic" but he used it to conceal a "self-centred arrogance".
"You designed your life to be close to boys - it suited you to be in education," he said.
"It gave you kudos and it also provided a source of boys."
Harris came to the attention of the authorities after British journalists working in Kenya were tipped off about the abuse.
Little known legislation was used where English courts have jurisdiction to try offences carried out by Britons abroad.
Kelvin Lay, lead investigator for the National Crime Agency, told Sky News: "We anticipate Simon Harris has been offending over four decades.
"We know of around 46 victims, but we anticipate that should we keep digging there would be many many more."
|Simon Harris - crimes were discovered after journalists in Kenya were tipped off|
He also admitted six counts of sexual assault on three teenage pupils at a public school in Devon where he taught Latin in the 1980s.
Victims' evidence was heard via video link from Kenya to the Birmingham court.
One young Kenyan man who made a complaint against Harris killed himself before jurors had reached their verdicts.
Harris was found guilty in December 2014.