Why the Tigers were unavailable in 1982

Why could the Tiger-class cruisers not be kept in service or reactivated for the Falklands War?

They were old hulls and could not be brought out of preservation quickly enough, even though usable six-inch ammunition could be located.

Their hulls had been laid down during World War II and were roughly forty years old by 1982. Late completion had already given them remarkably short careers as gun cruisers before helicopter conversion and reserve status. Usable six-inch ammunition could be found despite concerns about aged propellant. The decisive obstacle was time: careful mothball preservation made the ships slow to reactivate, so the crisis ended before either could be restored for deployment.