What was the name of the British Royal Yacht that entered service in 1953 and decommissioned on 11 December 1997?

Question

What kind of ship was the British ship HMS Hermes, laid down in January 1918, launched on 11 September 1919 but not commissioned until 1923, the first ship of its kind to be designed and built anywhere in the world?

Answer 1

The ans is -
Britannia