Henrik wikipedia is a useful starting point:
http://en.wikipedia.org/wiki/George_V_o ... ed_Kingdom
George the Fifth was a Constitutuional Monarch. His rolewas mainly symbolic....IMO.
He did relinquish (give away) all his German titles in 1917 and changed his surname from Saxe Coburg Gotha to Windsor. This was because anti-German feeling was very strong in Britain.... a bit peculiar really as changing your name doesn't change who you are......
The British Royal family were Princes of Saxe Coburg Gotha and Dukes of Saxony (male).
The Germany royalty who had British Titles and fought on the "wrong side" were stripped of their titles: affect the Royal/Ducal families of Hanover, Saxe Coburg Gotha, Brunswick... might some more?
Unfortunately this Anti-German sentiment has last a long time......
When Queen Victoria married Prince Albert of Saxe-Coburg-Gotha.... the British Royal Family changed from the Hanoverian dynasty to become the House of Saxe-Coburg-Gotha.
In 1917 the Royal Family changed to House of Windsor....
In 1960 a decision was made the QE2's descendants/kids would have the surname Mountbatten-Windsor, but the Royal House would still be Windsor.
A bit odd to celebrate Prince Philip's mother's maiden name/house......... Mountbatten.... which was changed in 1917 from Battenberg (a sub branch of the Royal House of Wurttemburg, as someone made a morganatic marriage (ie didn't marry someone royal enough).
In a fairer world..... Queen Elizabeth's children and the Royal House of Britain should be Schleswig-Holstein-Sonderburg-Glucksburg, because of Prince Philip's family roots.....