A post on Mr McMahon's Facebook page added: "The Duke lived a full life, dedicated to public service and displayed an unwavering sense of duty to our nation throughout.
"I hope the Royal Family have taken some comfort in the many millions of expressions of gratitude and appreciation for the Duke which have followed in the days since his death.
"The black border on the edges of this paper represents Parliament's traditional mourning paper, and often I will write to constituents in the same manner using this paper when I have heard that they have suffered a loss in their family."
