Why did Britain retain the County-class cruisers?

Why did the Royal Navy not replace the County-class cruisers before the Second World War, and what should have replaced them?

Treaty replacement rules kept them in service, while Britain did not want another ordinary eight-inch cruiser and preferred to wait for a more useful category.

The Royal Navy could not simply discard the Counties while treaty rules controlled when ships became replaceable. It also had little enthusiasm for building another conventional eight-inch heavy cruiser because the gun and category did not fit British needs well. Waiting preserved the possibility of a more useful large cruiser if treaty limits changed. The decision was therefore a mixture of legal timing, limited tonnage, and an unsatisfactory replacement category.