I messaged 'Bamford's UK auctions to let the know this card was an autopen. More that a week later they still have it up with a misleading description.

Royal Interest - Charles and Diana, Prince and Princess of Wales, 1989 Christmas signed card, autographed in MS black ink, enclosing a colour portrait photograph of the whole princely family, registered envelope with Buckingham Palace SW1A 1AA franked mark and crowned EIIR stamp in purple

Don't trust anyone. Do your own research before making a purchase. Too many people put ALL their trust in authenticators and auction houses. Trust yourself. 

Rant over