It used to be the case that, through the 1960s to the 1990s, the Royal Mint would, if possible, assign the same artist to a country's coinage. After Kenyatta's death in 1978, Daniel arap Moi became president of Kenya, and his portrait appeared on the coinage from 1980 onwards. Mr Sillman's superb portrait of President Moi can be seen below.Mr Sillman's grandson, Will Coles, recalls his working methods: "I used to watch him make the designs when I was a kid. They were usually about 30cm across when he was working on them, in plasticine on plastic coated wood, and always less than 10mm deep even at the thickest points. Then he'd cast them in dental plaster ('plaster of paris') and send those versions to the Royal Mint for scaling down."