Peter Ricketts, a former head of the Foreign Office, said today the invitation has put Queen Elizabeth II in a "very difficult position" because of the furor surrounding Trump's travel ban on refugees and people from some Muslim-majority countries.
He said in a letter to The Times that the invitation to Trump was "ill-judged" and should not have been made until Trump had spent some years in office.
The queen makes invitations to state visits on the advice of government officials, and traditionally hosts the visitor in Buckingham Palace.