THAT IS A BRITISH SHIP FILE A foia OR CONTACT THE BRITISH CONSULATE OR TRY THE BRISTISH GOOGLE SITE.

Hmmm... I hope you're open to the idea that the name of the ship might be wrong. Navies, and especially the British Royal Navy, have always been very particular about how they name their ships. The meaning of "indefensible" is completely opposite of the meaning of all the other names they give their ships. The Royal Navy ships (HMS means Her/His Majesty's Ship) had names like Dauntless, Impregnable, Indefatigable, Indomitable, Invincible, Unbeaten, etc...

I feel you mean HMS Indefatigable.... unwearying, unremitting.

Google, you will find an existing organisation set up for this Aircraft Carrier. 1939 to 1957. Good luck..EX RN.