An eight-ship battlecruiser force implies a rolling replacement cycle

How might the Royal Navy replace its older battlecruiser classes after the First World War?

Retire the oldest classes in the early 1920s, retain the newer ships longer, and use G3s and later construction to maintain about eight battlecruisers in two squadrons.

The oldest battlecruisers would leave first because rapid technical change made the Invincible and Indefatigable classes difficult to justify beyond the early 1920s. Lion, Queen Mary, and Tiger types could last later, depending on German strength and the need for a large scouting force. Four G3s, Hood, the two Renowns, and Tiger would provide roughly eight ships. That number points toward two four-ship squadrons sustained by a rolling programme of replacements rather than indefinite retention of every First World War hull.