Complex sentence: The regiment was titled the 19th (Alexandra, Princess of Wales's Own) Hussars after Alexandra, Princess of Wales in 1902 and, when Alexandra became Queen Consort in 1908, the name changed to the 19th (Queen Alexandra's Own Royal) Hussars.
Split into simpler sentences: The regiment was titled 19th (Alexandra, Princess of Wales's Own) Hussars after Alexandra, Princess of Wales. In 1908, when Alexandra became Queen Consort, the name changed to 19th (Queen Alexandra's Own Royal) Hussars.