I found in this website
www.nottingham.ac.uk/mss/online/ online-mss catalogues/cats/buchanan_intro.html (a catalogue of the papers of Sir Andrew Buchanan, a distinguished 19th -century diplomat ) this interesting note:
Letter from Sir Henry Ponsonby, Balmoral Castle, Scotland, to Sir Andrew Buchanan, Vienna, Austria; 5 June 1875:
"Informs him that the Queen has told him privately that she regrets the marriage of Prince Maximillian of Bavaria and Princess Amalie of Saxe Coburg Gotha; she [the Queen] has wished Amalie to marry a'good man' and fears that the Prince is not suitable; it is requested that he [Buchanan] confidentially pass on any information relating to the Prince and also express a personal opinion of him".