Why extra old cruisers do not postpone British replacement

Would a much larger force of C-, D-, and E-class cruisers buy the Royal Navy time before building replacements?

It would add useful numbers, but aging hulls and the need for modern County-class cruisers would keep replacement work moving.

More surviving light cruisers would give the Royal Navy a useful numerical base in the interwar period. County-class construction would still begin on roughly the historical schedule because the older ships would continue to age. Treaty rules also allowed overage cruisers to remain without counting in the same way against tonnage limits. The Navy could keep those hulls, but many lacked convincing modernization plans or new missions, so quantity did not eliminate the need for replacement.