According to Sweaters from Camp:

“The Prince of Wales had his portrait painted wearing a Fair Isle sweater, which greatly enhanced the popularity of Fair Isle knitting. The designer interpreted the sweater design for this vest from photographs of the portrait.”

Colors used:

4 ounces - FC45 camel; 2 ounces - 58 dark green; 1 ounce - 125 persimmon; 1 ounce - 143 chocolate; 1 ounce - 23 yellow; 1 ounce - 46 light yellow; 1 ounce - 9113 maroon.