Gesturing towards the youngsters, he said: "Definitely those boys there, they are going to ask me. Right away they are going to ask about school, and I have no answer for them."
Mr Hamisi befriended the couple when they came to stay in Diani, near the port city of Mombasa, in 2002. They went on to treat him "like a son", hiring him to look after the house they built in the village and often paying him even when they had no work for him.
Mrs Cooper would send him a text message roughly once a month asking after him and his family, and she and her partner would regularly wire him money for food and medicine.
For eight years the couple, from Long Sutton, Lincs, have also paid for Mr Hamisi's eldest children, aged eight and 13, and his nephew, 14, to attend a local private school. The annual fees came to 120,000 Kenyan shillings (£878).
In return, when Mr Hamisi's third child was born in 2009, he called him Foster in recognition of the life-changing help he received from the generous pair.
The Kenyan handyman said that Mrs Cooper told him in 2010 that she and her partner were "having problems with the tax collectors" in England and so they would not be able to send money as regularly, but he got the impression it was not an especially serious matter.
His forehead furrowed in disbelief and his hands shook when he learned on Friday about the jail sentence handed down to Mr Foster and Mrs Cooper at Lincoln Crown Court this week for the six-year cannabis-growing operation that netted them an estimated £400,000.
"That is very, very strange to me," he said. "I was just not aware of that. I don't know if it's true."
Villagers in Diani also recalled how Mrs Cooper paid at least £4,000 in 2008 so a young man called Wilson Kenji could undergo eight hours of emergency surgery on his left leg, which had been crushed in a bus accident the year before.
The doctors who operated on Mr Kenji said he would have died in two days if they had not seen him when they did.
Mr Kenji, who described Mrs Cooper as a "very kind lady", had a second operation two years ago. He now walks with crutches on a platform shoe, but says he does not feel much pain and has managed to find a job as a restaurant cashier.
Mr Foster and Mrs Cooper never showed off about their giving but liked to help people they knew who were having difficulties, among them expatriates as well as Africans, according to a close European friend of the couple who lives in Diani.
The friend, who did not want to be named, said the couple were involved in buying and selling properties but Mrs Cooper was always "a little bit vague" about how she spent her time.
It became clear that they were having financial troubles of their own when in 2010 they arranged to sell a house in the Kenyan village for a very low price.
Locals said that the English couple, who have been compared to Robin Hood for the way they funded their charity through crime, kept themselves to themselves when they visited Diani, relaxing on the beach or catching up with a few close friends.
Mr Foster enjoyed a beer and a gin-and-tonic, but Mrs Cooper was teetotal - and the villagers were adamant that they never saw the couple smoking cannabis.
Passing sentence this week, Judge Sean Morris accepted that they were of "positive good character" but condemned their involvement in drug dealing.
He told them: "You were growing it on a significant scale, jetting off to Kenya on it. I am sure you were doing good things in Kenya with your drugs money, whether that was to appease your consciences I can only speculate."
