The source told the Sunday Times: “This business of Prince Charles and Prince William not being there for the Trump visit was a snub.

“They simply refused to attend. It’s a very, very unusual thing for the Queen to be there on her own.

“Usually she is accompanied by somebody. Prince Charles has been substituting for Phillip a lot lately.”

And speaking of Phillip, who retired from formal royal duties recently, the source said: “He goes to what he wants to go to, and if he wanted to be there he could have been.”