What is exactly Royalty? I think it is a term used and abused. I think the worst abuse was by Ronald Ferguson, who going to a massage parlour asked their opinion about dealing with royalty, meaning himself. He is a descendant of King Charles II, but in my opinion, he definitely is not a royal.
His daughter while married to the Duke of York, I think she was, but now, as mother of two royal princesses, is she still to be regarded as royalty?
Say before World War One, members of royal families were allowed only to marry with people recorded in the Almanach de Gotha.
Does this imply that we should regard all the families recorded in the Almanach de Gotha as royalty? I think not.
The Almanac de Gotha divided these families into three levels. The family of Queen Paola of Belgium belongs in the 3rd (and lowest ?) level.
In the most recent Almanch de Gotha I have, interestingly starts the first segment with the kings of Afghanistan. I would love to have seen a crownprince or any royal princess in Europe wanting to marry a member of that family

Here are the families of the first level
kings of Afghanistan
Albania (the Wied family)
Anhalt
the House of Austria
the House of Baden
the kings of Bavaria
the kings of Belgium
the House of Bonaparte
the house de Bourbon
the house de Braganca
the house of Brunswick-Luneburg (Hannover)
kings of Bulgaria
kings of Denmark
kings of Egypt
kings of Spain
imperial family of Ethiopia
kings of Great Britain
the kings of Greece
the House of Hedjaz
the House of Hessen
the House of Hohenzollern (see Prussia)
the House of Holstein
the kings of Italy
the Imperial family of Japan
the House of Liechtenstein
the House of Lippe
the House of Luxembourg
the House of Mecklenburg
the House of Monaco
the House of Montenegro
the House of Nepal
the kings of Norway
the House of Oldenburg
the house of Oman
the House of Osman
the Kingdom of the Netherlands
the Imperial family of Persia
the House of Prussia
the House of Reuss
the Imperial family of Russia
the kings of Roumania
the kings of Saxony
the House of Saxe-Weimar-Eisenach
the House of Saxe-Meiningen-Hildburghausen
the House of Saxe-Altenburg
the House of Saxe-Coburg-Gotha
the House of Schaumburg-Lippe
the House of Schwarzburg
the kings of Serbia
the kings of Siam
the kings of Sweden
the House of Waldeck
the House of Wurttemberg
The second and third part have many more families.
Now the question is, where do you draw the line, who is and who is not "royalty" ?
With best wishes
Leo van de Pas,
Canberra, Australia