Mr McGrady said: “The most incredible sweet white Windsor peaches grew on the estate too in my day.
“We’d have to lock them away in the kitchens because everyone wanted to taste them.
“The Queen always looked forward to those but she’d have to wait until they were in season.”
“Why would they buy packaged food when the queen has 20 personal chefs?”
Mr McGrady would puree the young princes’ first meals of steamed apples and pears from the Queen’s Sandringham estate.
He explained that the purees had to be sieved twice to be fully sure there were no remaining lumps.
The royal chef added: “As they got older, you’d have one chef in the kitchen doing the chicken, one doing the veg, and then it would all be blended together; it was a major operation cooking for them.”
Mr McGrady now lives in America and has cooked for five US Presidents.