Why Malta no longer hosts a major fleet base

Why is there no longer a large naval base on strategically located Malta?

Mainly politics, in the answer's judgment, combined with a location that served British needs more strongly than those of other major navies.

Malta's loss of a major naval base is attributed largely to politics, despite its location's particular value to Britain. The Royal Navy lacked other dependable territory nearby and could secure the island with naval power. Other major Mediterranean states gained less from using Malta. The United States was a possible alternative occupant but preferred a base in Italy. A historical comparison recalls Malta's earlier use by the Knights Hospitaller, whose identity is clarified after the initial reference to the Knights of Rhodes.