Why Britain delayed a heavy-cruiser project

Why did the Royal Navy take so long to begin a First World War-era heavy-cruiser project?

It was building other ships, still deciding what cruisers it needed, and already had many battlecruisers and light cruisers for the North Sea problem.

The Royal Navy was building other ships and still deciding what cruisers it wanted. Its numerous battlecruisers and light cruisers already served the concentrated North Sea campaign against Germany. That combination made a separate heavy-cruiser project difficult to justify during the First World War.