Invincible's condition when a hull extension was discussed

How worn out were the Invincible-class carriers when a hull extension was being considered?

They are judged worn enough to make further service extension undesirable, without a detailed condition survey.

The condition judgment is emphatic: the Invincible-class ships were already worn enough that a hull extension seemed undesirable. No measurements of structural fatigue, machinery condition, or remaining service life accompany this brief reply.