I think gdella may have been refering to the oldest royal of all the royal families, or just the oldest of the British Royal Family. I think she may have been the oldest of both. The only other one I can think of off the top of my head is Anna Battenberg 1874-1971, which would have put her somewhere around 97, younger than Alice.
In the Guinness book of records it was a Bourbon Princess who lived longer than either Alice of athlone or Anna of montenegro/Battenberg...
I couldn't find out who it was--there are so many Bourbons!
Here's what one site had though:
Lady Alice Montagu-Douglas-Scott, Duchess of Gloucester 25 Dec 1901 29 Oct 2004 (102 )
Lady Elizabeth Bowes-Lyon, Queen (Mother) of Great Britain 4 Aug 1900 30 Mar 2002 (101 )
Infanta Alicia of Spain 29 Jun 1876 20 Jan 1975 (98 )
Duchess Altburg of Oldenburg, Princess of Waldeck & Pyrmont 19 May 1903 16 June 2001 (98)
Princess Alice of Albany, Countess of Athlone 25 Feb 1883 13 Jan 1981 (97)
Princess Eduarda of Liechtenstein, Countess zu Pappenheim 16 Oct 1903 13 Jul 2001 (97)
Princess Marie Adelaide of Lippe, Princess Reuss 30 Aug 1895 25 Jan 1993 (97)
Princess Margarete of Thurn & Taxis, Princess Gaetano of Bourbon-Parma 8 Nov 1909 (97)
Princess Rosemary of Salm-Salm, Archduchess Hubert Salvator of Austria-Tuscany 13 Apr 1904 3 May 2001 (97)
Princess Margrethe of Denmark, Princess René of Bourbon-Parma 17 Sep 1895 18 Sep 1992 (97)
Princess Zita of Bourbon-Parma, Empress of Austria and Queen of Hungary 9 May 1892 14 Mar 1989 (96)
Countess Klara-Maria von Korff gt Schmissing-Kerssenbrock, Duchess of Saxe-Meiningen 31 May 1895 10 Feb 1992 (96 )
Princess Anna of Montenegro, Princess Franz Joseph of Battenberg 18 Aug 1874 22 Apr 1971 (96)
Princess Maria Antonia of Portugal, Duchess of Parma 28 Nov 1862 14 May 1959 (96)
Prince Leopold zu Schaumburg-Lippe 21 Feb 1910 25 Jan 2006 (95 )
Prince Lennart of Sweden, Count Bernadotte of Visborg 8 May 1909 21 Dec 2004 (95) (Finally a male on the list!)
Prince Filiberto of Savoy, Duke of Genoa 10 Mar 1895 7 Sep 1990 (95)
Princess Margaret of Connaught's son, Carl Johan was born 31 Oct 1916 so he's 91 now--inching his way up there! He's QV's last surviving great-grandson and one of just 2 great-grandchildren left now along with Katherine Brandram (nee Greece) who is 94.